smb/server: add comment to FileSystemName of FileFsAttributeInformation

Explained why FileSystemName is always set to "NTFS".

Link: https://github.com/namjaejeon/ksmbd/commit/84392651b0b740d2f59bcacd3b4cfff8ae0051a0
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
1 file changed