knfsd: remove bogus BUG_ON() call from nfsd4_locku

The code checks for a NULL filp and handles it gracefully just before
this BUG_ON.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -4294,7 +4294,6 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		status = nfserr_lock_range;
 		goto out;
 	}
-	BUG_ON(!filp);
 	locks_init_lock(&file_lock);
 	file_lock.fl_type = F_UNLCK;
 	file_lock.fl_owner = (fl_owner_t)lockowner(stp->st_stateowner);