Fix more clobbers

Author: Grazfather

port/wch/ch32v/src/cpus/main.zig

@@ -282,7 +282,26 @@ pub const startup_logic = struct {
         @export(&startup_logic._system_init, .{ .name = "_system_init" });
         asm volatile (
             \\jal _system_init
-        );
+            // We have clobber all caller-saved registers
+            ::: .{
+                .x1 = true,
+                .x5 = true,
+                .x6 = true,
+                .x7 = true,
+                .x10 = true,
+                .x11 = true,
+                .x12 = true,
+                .x13 = true,
+                .x14 = true,
+                .x15 = true,
+                .x16 = true,
+                .x17 = true,
+                .x28 = true,
+                .x29 = true,
+                .x30 = true,
+                .x31 = true,
+                .memory = true,
+            });
 
         // Load the address of the `microzig_main` function into the `mepc` register
         // and transfer control to it using the `mret` instruction.