net: ethernet: aquantia: remove another redundant err check

The check on err < 0 is redundant and can be removed. Detected
by CoverityScan, CID#1398318 ("Logically Dead Code")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/aq_ring.c

@@ -304,8 +304,6 @@ int aq_ring_rx_fill(struct aq_ring_s *self)
 
 		buff = NULL;
 	}
-	if (err < 0)
-		goto err_exit;
 
 err_exit:
 	if (err < 0) {