xen-netback: remove redundent parameter in netbk_count_requests

Tracking down from the caller, first_idx is always equal to vif->tx.req_cons.
Remove it to avoid confusion.
Suggested-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/xen-netback/netback.c

@@ -928,7 +928,6 @@ static void netbk_fatal_tx_err(struct xenvif *vif)
 
 static int netbk_count_requests(struct xenvif *vif,
 				struct xen_netif_tx_request *first,
-				RING_IDX first_idx,
 				struct xen_netif_tx_request *txp,
 				int work_to_do)
 {
@@ -1005,7 +1004,7 @@ static int netbk_count_requests(struct xenvif *vif,
 	} while ((txp++)->flags & XEN_NETTXF_more_data);
 
 	if (drop_err) {
-		netbk_tx_err(vif, first, first_idx + slots);
+		netbk_tx_err(vif, first, cons + slots);
 		return drop_err;
 	}
 
@@ -1470,8 +1469,7 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
 				continue;
 		}
 
-		ret = netbk_count_requests(vif, &txreq, idx,
-					   txfrags, work_to_do);
+		ret = netbk_count_requests(vif, &txreq, txfrags, work_to_do);
 		if (unlikely(ret < 0))
 			continue;