PCI/PTM: Build debugfs code only if CONFIG_DEBUG_FS is enabled

JIRA: https://issues.redhat.com/browse/RHEL-107597
Upstream Status: 5aa326a

commit 5aa326a
Author: Manivannan Sadhasivam <mani@kernel.org>
Date:   Sun Jun 8 09:03:05 2025 +0530

    PCI/PTM: Build debugfs code only if CONFIG_DEBUG_FS is enabled

    Otherwise, the following build error will happen for CONFIG_DEBUG_FS=n &&
    CONFIG_PCIE_PTM=y:

      drivers/pci/pcie/ptm.c:498:25: error: redefinition of 'pcie_ptm_create_debugfs'
        498 | struct pci_ptm_debugfs *pcie_ptm_create_debugfs(struct device *dev, void *pdata,
            |                         ^
      ./include/linux/pci.h:1915:2: note: previous definition is here
       1915 | *pcie_ptm_create_debugfs(struct device *dev, void *pdata,
            |  ^
      drivers/pci/pcie/ptm.c:546:6: error: redefinition of 'pcie_ptm_destroy_debugfs'
        546 | void pcie_ptm_destroy_debugfs(struct pci_ptm_debugfs *ptm_debugfs)
            |      ^
      ./include/linux/pci.h:1918:1: note: previous definition is here
       1918 | pcie_ptm_destroy_debugfs(struct pci_ptm_debugfs *ptm_debugfs) { }
            |

    Fixes: 1328334 ("PCI: Add debugfs support for exposing PTM context")
    Reported-by: Eric Biggers <ebiggers@kernel.org>
    Closes: https://lore.kernel.org/linux-pci/20250607025506.GA16607@sol
    Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
    Tested-by: Eric Biggers <ebiggers@kernel.org>
    Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
    Link: https://patch.msgid.link/20250608033305.15214-1-manivannan.sadhasivam@linaro.org

Signed-off-by: Myron Stowe <mstowe@redhat.com>

Author: Myron Stowe

drivers/pci/pcie/ptm.c

@@ -254,6 +254,7 @@ bool pcie_ptm_enabled(struct pci_dev *dev)
 }
 EXPORT_SYMBOL(pcie_ptm_enabled);
 
+#if IS_ENABLED(CONFIG_DEBUG_FS)
 static ssize_t context_update_write(struct file *file, const char __user *ubuf,
 			     size_t count, loff_t *ppos)
 {
@@ -552,3 +553,4 @@ void pcie_ptm_destroy_debugfs(struct pci_ptm_debugfs *ptm_debugfs)
 	debugfs_remove_recursive(ptm_debugfs->debugfs);
 }
 EXPORT_SYMBOL_GPL(pcie_ptm_destroy_debugfs);
+#endif