SUNRPC: task_run_action should display tk_callback

This shows up in every RPC:

     kworker/4:1-19772 [004]  3467.373443: rpc_task_run_action:  task:4711@2 flags=0e81 state=0005 status=0 action=call_status
     kworker/4:1-19772 [004]  3467.373444: rpc_task_run_action:  task:4711@2 flags=0e81 state=0005 status=0 action=call_status

What's actually going on is that the first iteration of the RPC
scheduler is invoking the function in tk_callback (in this case,
xprt_timer), then invoking call_status on the next iteration.

Feeding do_action, rather than tk_action, to the "task_run_action"
trace point will now always display the correct FSM step.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/sched.c

@@ -770,7 +770,7 @@ static void __rpc_execute(struct rpc_task *task)
 			if (do_action == NULL)
 				break;
 		}
-		trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
+		trace_rpc_task_run_action(task->tk_client, task, do_action);
 		do_action(task);
 
 		/*