cifsd: fix incorrect comments

kernel test bot reports some incorrect comments.
This patch fixes these comments.

Reported-by: kernel test bot <lkp@intel.com>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>