rxrpc: Trace packet transmission

Trace successful packet transmission (kernel_sendmsg() succeeded, that is)
in AF_RXRPC.  We can share the enum that defines the transmission points
with the trace_rxrpc_tx_fail() tracepoint, so rename its constants to be
applicable to both.

Also, save the internal call->debug_id in the rxrpc_channel struct so that
it can be used in retransmission trace lines.

Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/conn_client.c

@@ -590,6 +590,7 @@ static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
 	 */
 	smp_wmb();
 	chan->call_id	= call_id;
+	chan->call_debug_id = call->debug_id;
 	rcu_assign_pointer(chan->call, call);
 	wake_up(&call->waitq);
 }