xen-netback: remove unused variables pending_idx and index

building with gcc and W=1 reports
drivers/net/xen-netback/netback.c:886:21: error: variable
  ‘pending_idx’ set but not used [-Werror=unused-but-set-variable]
  886 |                 u16 pending_idx;
      |                     ^~~~~~~~~~~

pending_idx is not used so remove it.  Since index was only
used to set pending_idx, remove index as well.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20230226163429.2351600-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/xen-netback/netback.c

@@ -883,11 +883,9 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
 		struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
 		struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
 		unsigned int extra_count;
-		u16 pending_idx;
 		RING_IDX idx;
 		int work_to_do;
 		unsigned int data_len;
-		pending_ring_idx_t index;
 
 		if (queue->tx.sring->req_prod - queue->tx.req_cons >
 		    XEN_NETIF_TX_RING_SIZE) {
@@ -983,9 +981,6 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
 			break;
 		}
 
-		index = pending_index(queue->pending_cons);
-		pending_idx = queue->pending_ring[index];
-
 		if (ret >= XEN_NETBK_LEGACY_SLOTS_MAX - 1 && data_len < txreq.size)
 			data_len = txreq.size;