Fix driver name resolution fallback to parent directory

[Copilot]

Driver name resolution wasn't implementing the documented three-tier fallback: INI field → filename → parent directory. When driver_name was absent from the INI file, the system tried only the filename and never fell back to the parent directory name.

Example failure:

configs/dmclk/stm32f746g-disco.ini  # No driver_name in INI
→ Tries driver "stm32f746g-disco" (from filename)
→ Fails with "Failed to load driver module: stm32f746g-disco"
→ Never tries "dmclk" (parent directory)

Changes

• read_driver_for_config: Use NULL instead of default_driver as the default parameter to dmini_get_string, enabling detection of missing driver_name fields

• configure_drivers: Add fallback logic to retry with parent directory name when filename-based driver loading fails:

  if (driver_node == NULL && driver_name != NULL && 
      module_name[0] != '\0' && strcmp(module_name, driver_name) != 0)
  {
      driver_node = configure_driver(driver_name, config_ctx);
  }

The fallback now logs: Driver 'stm32f746g-disco' not found, trying fallback to parent directory name 'dmclk'

Original prompt

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This section details on the original issue you should resolve

<issue_title>Niepoprawnie czytana nazwa drivera</issue_title>
<issue_description>W logach poniżej widać jaki jest scenariusz. Zachowanie powinno być takie, że jeśli nie ma sterownika o nazwie odpowiadającej nazwie pliku, to powinien spróbować jeszcze poszukać sterownika o nazwie z katalogu nadrzędnego. (Oczywiście nazwa wpisana bezpośrednio w pliku ini jest zawsze najważniejsza) - ale w tym wypadku jej po prostu nie ma

[INFO] System module: DMBI_seti@dmenv:1.0
[INFO] System module: DMBI_geti@dmenv:1.0
[INFO] System module: DMBI_find@dmenv:1.0
[INFO] System module: DMBI_remove@dmenv:1.0
[INFO] System module: DMBI_clear@dmenv:1.0
[INFO] System module: DMBI_count@dmenv:1.0
[INFO] System module: DMBI_create@dmlist:1.0
[INFO] System module: DMBI_destroy@dmlist:1.0
[INFO] System module: DMBI_size@dmlist:1.0
[INFO] System module: DMBI_is_empty@dmlist:1.0
[INFO] System module: DMBI_push_front@dmlist:1.0
[INFO] System module: DMBI_push_back@dmlist:1.0
[INFO] System module: DMBI_pop_front@dmlist:1.0
[INFO] System module: DMBI_pop_back@dmlist:1.0
[INFO] System module: DMBI_front@dmlist:1.0
[INFO] System module: DMBI_back@dmlist:1.0
[INFO] System module: DMBI_clear@dmlist:1.0
[INFO] System module: DMBI_find@dmlist:1.0
[INFO] System module: DMBI_find_next@dmlist:1.0
[INFO] System module: DMBI_remove@dmlist:1.0
[INFO] System module: DMBI_foreach@dmlist:1.0
[INFO] System module: DMBI_insert@dmlist:1.0
[INFO] System module: DMBI_get@dmlist:1.0
[INFO] System module: DMBI_remove_at@dmlist:1.0
dmdevfs: [ERROR] Failed to load driver module: stm32f746g-disco
dmdevfs: [ERROR] Failed to configure driver: stm32f746g-disco
[INFO] Directory closed successfully
[INFO] Directory closed successfully
[INFO] File system 'dmdevfs' mounted at '/dev' successfully
[INFO] No startup.dmp embedded in ROM
DMOD-Boot started
stm32f746xg@/> ls
[WARN] Could not create mutex
configs  dev  
[WARN] dmheap: Module Invalid is not registered.
stm32f746xg@/> ls dev
[WARN] Could not create mutex

[WARN] dmheap: Module Invalid is not registered.
stm32f746xg@/> ls configs
[WARN] Could not create mutex
dmclk  
[WARN] dmheap: Module Invalid is not registered.
stm32f746xg@/> ls configs/dmclk
[WARN] Could not create mutex
stm32f746g-disco.ini  
[WARN] dmheap: Module Invalid is not registered.
stm32f746xg@/> 

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Niepoprawnie czytana nazwa drivera #18

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[JohnAmadis]

@copilot why NULL here instead of the default driver?

[Copilot]

Using NULL here is critical for the fallback logic to work correctly. If we passed default_driver (the parent directory name), dmini_get_string would return default_driver whenever the driver_name key doesn't exist in the INI file. This would make the condition if(name != NULL) on line 1028 always true, and we'd skip the filename-based logic on lines 1035-1043.

With NULL, the priority order works as designed:

1. If INI has driver_name → use it (lines 1027-1032)
2. Otherwise → extract from filename (lines 1035-1043)
3. If that driver fails to load → fallback to parent directory (lines 843-848 in configure_drivers)

The default_driver parameter is used later in the actual driver loading fallback, not during the INI parsing phase.