rxrpc: checking for IS_ERR() instead of NULL

The rxrpc_lookup_peer() function returns NULL on error, it never returns
error pointers.

Fixes: 8496af50eb38 ('rxrpc: Use RCU to access a peer's service connection tree')
Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: David Howells <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/rxrpc/conn_service.c

···
 
 	if (!peer) {
 		peer = rxrpc_lookup_peer(local, srx, GFP_NOIO);
-		if (IS_ERR(peer))
+		if (!peer)
 			goto enomem;
 	}