SUNRPC: remove BUG_ON in svc_register

Instead of calling BUG_ON(), do a WARN_ON_ONCE() and return -EINVAL.
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/svc.c

@@ -950,7 +950,9 @@ int svc_register(const struct svc_serv *serv, struct net *net,
 	unsigned int		i;
 	int			error = 0;
 
-	BUG_ON(proto == 0 && port == 0);
+	WARN_ON_ONCE(proto == 0 && port == 0);
+	if (proto == 0 && port == 0)
+		return -EINVAL;
 
 	for (progp = serv->sv_program; progp; progp = progp->pg_next) {
 		for (i = 0; i < progp->pg_nvers; i++) {