net: ethernet: aeroflex: fix potential memory leak in greth_start_xmit_gbit()

The greth_start_xmit_gbit() returns NETDEV_TX_OK without freeing skb
in case of skb->len being too long, add dev_kfree_skb() to fix it.

Fixes: d4c41139df6e ("net: Add Aeroflex Gaisler 10/100/1G Ethernet MAC driver")
Signed-off-by: Wang Hai <[e-mail]>
Reviewed-by: Gerhard Engleder <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/aeroflex/greth.c

···
 
 	if (unlikely(skb->len > MAX_FRAME_SIZE)) {
 		dev->stats.tx_errors++;
-		goto out;
+		goto len_error;
 	}
 
 	/* Save skb pointer. */
···
 map_error:
 	if (net_ratelimit())
 		dev_warn(greth->dev, "Could not create TX DMA mapping\n");
+len_error:
 	dev_kfree_skb(skb);
 out:
 	return err;