net: ethernet: mtk_eth_soc: fix error handling in mtk_open()

If mtk_start_dma() fails, invoke phylink_disconnect_phy() to perform
cleanup. phylink_disconnect_phy() contains the put_device action. If
phylink_disconnect_phy is not performed, the Kref of netdev will leak.

Fixes: b8fc9f30 ("net: ethernet: mediatek: Add basic PHYLINK support")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/20221117111356.161547-1-liujian56@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -2996,8 +2996,10 @@ static int mtk_open(struct net_device *dev)
 		int i;
 
 		err = mtk_start_dma(eth);
-		if (err)
+		if (err) {
+			phylink_disconnect_phy(mac->phylink);
 			return err;
+		}
 
 		for (i = 0; i < ARRAY_SIZE(eth->ppe); i++)
 			mtk_ppe_start(eth->ppe[i]);