SUNRPC: Remove trace_xprt_complete_rqst()

Request completion is already recorded by an "rpc_task_wakeup
queue=xprt_pending" trace record. A subsequent rpc_xdr_recvfrom
trace record shows the number of bytes received.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>