ksmbd: fix kernel-doc comment of ksmbd_vfs_kern_path_locked()

Fix argument list that the kdoc format and script verified in
ksmbd_vfs_kern_path_locked().

fs/smb/server/vfs.c:1207: warning: Function parameter or member 'parent_path'
not described in 'ksmbd_vfs_kern_path_locked'

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>