fix(kernel): devfs last_slash/file_name 改用裸 str，修复 i8* 赋给 i8** 导致设备注册空名

VKernel/Kernel/drivers/devfs/devfs.vp

@@ -215,13 +215,13 @@ class _DevFSObject:
         string.memset(c.Addr(path_copy), 0, PATH_BUFFER_SIZE)
         string.strcpy(path_copy, path)
 
-        last_slash: str | t.CPtr = string.strrchr(path_copy, '/')
+        last_slash: str = string.strrchr(path_copy, '/')
 
         if not last_slash: return -1
 
         last_slash[0] = '\0'
         dir_path = path_copy
-        file_name: str | t.CPtr = last_slash + 1
+        file_name: str = last_slash + 1
 
         dir_ptr: devfs_directory | t.CPtr = self.find_or_create_directory(dir_path)
         if not dir_ptr: return -1
@@ -250,13 +250,13 @@ class _DevFSObject:
         string.memset(c.Addr(path_copy), 0, PATH_BUFFER_SIZE)
         string.strcpy(path_copy, path)
 
-        last_slash: str | t.CPtr = string.strrchr(path_copy, '/')
+        last_slash: str = string.strrchr(path_copy, '/')
 
         if not last_slash: return -1
 
         last_slash[0] = '\0'
         dir_path = path_copy
-        file_name: str | t.CPtr = last_slash + 1
+        file_name: str = last_slash + 1
 
         dir_ptr: devfs_directory | t.CPtr = devfs_directory.find(dir_path, self.root_directory)
         if not dir_ptr: return -1