cifs: Clear modified attribute bit from inode flags

Clear CIFS_INO_MODIFIED_ATTR bit from inode flags after
updating mtime and ctime

Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: Steve French <stfrench@microsoft.com>