net: ag71xx: remove dead code path

The "err" is always zero, so the following branch can never be executed:
if (err) {
	ndev->stats.rx_dropped++;
	kfree_skb(skb);
}
Therefore, the "if" statement can be removed.

Use "ndev->stats.rx_errors" to count "napi_build_skb()" failure
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/20240911135828.378317-1-usama.anjum@collabora.comSigned-off-by: Qianqiang Liu <qianqiang.liu@163.com>
Link: https://patch.msgid.link/20240913014731.149739-1-qianqiang.liu@163.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/atheros/ag71xx.c

@@ -1616,7 +1616,6 @@ static int ag71xx_rx_packets(struct ag71xx *ag, int limit)
 		unsigned int i = ring->curr & ring_mask;
 		struct ag71xx_desc *desc = ag71xx_ring_desc(ring, i);
 		int pktlen;
-		int err = 0;
 
 		if (ag71xx_desc_empty(desc))
 			break;
@@ -1639,6 +1638,7 @@ static int ag71xx_rx_packets(struct ag71xx *ag, int limit)
 
 		skb = napi_build_skb(ring->buf[i].rx.rx_buf, ag71xx_buffer_size(ag));
 		if (!skb) {
+			ndev->stats.rx_errors++;
 			skb_free_frag(ring->buf[i].rx.rx_buf);
 			goto next;
 		}
@@ -1646,14 +1646,9 @@ static int ag71xx_rx_packets(struct ag71xx *ag, int limit)
 		skb_reserve(skb, offset);
 		skb_put(skb, pktlen);
 
-		if (err) {
-			ndev->stats.rx_dropped++;
-			kfree_skb(skb);
-		} else {
-			skb->dev = ndev;
-			skb->ip_summed = CHECKSUM_NONE;
-			list_add_tail(&skb->list, &rx_list);
-		}
+		skb->dev = ndev;
+		skb->ip_summed = CHECKSUM_NONE;
+		list_add_tail(&skb->list, &rx_list);
 
 next:
 		ring->buf[i].rx.rx_buf = NULL;