ksmbd: fix bug on trap in smb2_lock

If lock count is greater than 1, flags could be old value.
It should be checked with flags of smb_lock, not flags.
It will cause bug-on trap from locks_free_lock in error handling
routine.

Cc: [e-mail]
Reported-by: Norbert Szetei <[e-mail]>
Tested-by: Norbert Szetei <[e-mail]>
Signed-off-by: Namjae Jeon <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/smb/server/smb2pdu.c

···
 retry:
 		rc = vfs_lock_file(filp, smb_lock->cmd, flock, NULL);
 skip:
-		if (flags & SMB2_LOCKFLAG_UNLOCK) {
+		if (smb_lock->flags & SMB2_LOCKFLAG_UNLOCK) {
 			if (!rc) {
 				ksmbd_debug(SMB, "File unlocked\n");
 			} else if (rc == -ENOENT) {