rxrpc: Trace UDP transmission failure

Add a tracepoint to log transmission failure from the UDP transport socket
being used by AF_RXRPC.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/local_event.c b/net/rxrpc/local_event.c
index 93b5d91..8325f1b 100644
--- a/net/rxrpc/local_event.c
+++ b/net/rxrpc/local_event.c
@@ -71,7 +71,8 @@ static void rxrpc_send_version_request(struct rxrpc_local *local,
 
 	ret = kernel_sendmsg(local->socket, &msg, iov, 2, len);
 	if (ret < 0)
-		_debug("sendmsg failed: %d", ret);
+		trace_rxrpc_tx_fail(local->debug_id, 0, ret,
+				    rxrpc_tx_fail_version_reply);
 
 	_leave("");
 }