SUNRPC: Replace dprintk() call site in xprt_prepare_transmit

Generate a trace event when an RPC request is queued without being
sent immediately.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index 781277b..9746a72 100644
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -1093,6 +1093,7 @@ DECLARE_EVENT_CLASS(xprt_writelock_event,
 
 DEFINE_WRITELOCK_EVENT(reserve_xprt);
 DEFINE_WRITELOCK_EVENT(release_xprt);
+DEFINE_WRITELOCK_EVENT(transmit_queued);
 
 DECLARE_EVENT_CLASS(xprt_cong_event,
 	TP_PROTO(