rxrpc: Trace rxrpc_call usage

Add a trace event for debuging rxrpc_call struct usage.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index 865078d..27b9eca 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -270,6 +270,7 @@
 		call = hlist_entry(peer->error_targets.first,
 				   struct rxrpc_call, error_link);
 		hlist_del_init(&call->error_link);
+		rxrpc_see_call(call);
 
 		queue = false;
 		write_lock(&call->state_lock);