s390/qeth: support GRO flush timer

Switch to napi_complete_done(), and thus enable delayed GRO flushing.
The timeout is configured via /sys/class/net/<if>/gro_flush_timeout.

Default timeout is 0, so no change in behaviour.
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core_main.c

@@ -5370,7 +5370,7 @@ int qeth_poll(struct napi_struct *napi, int budget)
 		}
 	}
 
-	napi_complete(napi);
+	napi_complete_done(napi, work_done);
 	if (qdio_start_irq(card->data.ccwdev, 0))
 		napi_schedule(&card->napi);
 out: