net: stmmac: fix system hang if change mac address after interface ifdown

Fix system hang with below sequences:
~# ifconfig ethx down
~# ifconfig ethx hw ether xx:xx:xx:xx:xx:xx

After ethx down, stmmac all clocks gated off and then register access causes
system hang.

Fixes: 5ec55823 ("net: stmmac: add clocks management for gmac driver")
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -5891,12 +5891,21 @@ static int stmmac_set_mac_address(struct net_device *ndev, void *addr)
 	struct stmmac_priv *priv = netdev_priv(ndev);
 	int ret = 0;
 
+	ret = pm_runtime_get_sync(priv->device);
+	if (ret < 0) {
+		pm_runtime_put_noidle(priv->device);
+		return ret;
+	}
+
 	ret = eth_mac_addr(ndev, addr);
 	if (ret)
-		return ret;
+		goto set_mac_error;
 
 	stmmac_set_umac_addr(priv, priv->hw, ndev->dev_addr, 0);
 
+set_mac_error:
+	pm_runtime_put(priv->device);
+
 	return ret;
 }