net: ena: remove set but not used variable 'rx_ring'

drivers/net/ethernet/amazon/ena/ena_netdev.c: In function ena_xdp_xmit_buff:
drivers/net/ethernet/amazon/ena/ena_netdev.c:316:19: warning:
 variable rx_ring set but not used [-Wunused-but-set-variable]

commit 548c4940 ("net: ena: Implement XDP_TX action")
left behind this unused variable.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -313,7 +313,6 @@ static int ena_xdp_xmit_buff(struct net_device *dev,
 	struct ena_com_tx_ctx ena_tx_ctx = {0};
 	struct ena_tx_buffer *tx_info;
 	struct ena_ring *xdp_ring;
-	struct ena_ring *rx_ring;
 	u16 next_to_use, req_id;
 	int rc;
 	void *push_hdr;
@@ -324,8 +323,6 @@ static int ena_xdp_xmit_buff(struct net_device *dev,
 	req_id = xdp_ring->free_ids[next_to_use];
 	tx_info = &xdp_ring->tx_buffer_info[req_id];
 	tx_info->num_of_bufs = 0;
-	rx_ring = &xdp_ring->adapter->rx_ring[qid -
-		  xdp_ring->adapter->xdp_first_ring];
 	page_ref_inc(rx_info->page);
 	tx_info->xdp_rx_page = rx_info->page;