[CIFS] Add mmap for direct, nobrl cifs mount types

without mmap functions in file_ops OpenOffice can't save changes in
existing document. The same situation you can see with gedit. Also, a.out
format of files can't be executed without mmap.

Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsfs.c

@@ -808,6 +808,7 @@ const struct file_operations cifs_file_direct_nobrl_ops = {
 	.release = cifs_close,
 	.fsync = cifs_fsync,
 	.flush = cifs_flush,
+	.mmap = cifs_file_mmap,
 	.splice_read = generic_file_splice_read,
 #ifdef CONFIG_CIFS_POSIX
 	.unlocked_ioctl  = cifs_ioctl,