sfc: Wrap __efx_rx_packet() with efx_rx_flush_packet()

The pipeline mechanism will need to change a bit for scattered
packets.  Add a wrapper to insulate efx_process_channel() from this.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

drivers/net/ethernet/sfc/rx.c

@@ -465,8 +465,7 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
 	 */
 	rx_buf->len = len - efx->type->rx_buffer_hash_size;
 out:
-	if (channel->rx_pkt)
-		__efx_rx_packet(channel, channel->rx_pkt);
+	efx_rx_flush_packet(channel);
 	channel->rx_pkt = rx_buf;
 }