net: stmicro: handle clk_prepare() failure during init

In case clk_prepare() fails, capture and propagate the error code up the
stack. If regulator_enable() was called earlier, properly unwind it by
calling regulator_disable().
Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210503115736.2104747-22-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c

@@ -30,7 +30,7 @@ struct sunxi_priv_data {
 static int sun7i_gmac_init(struct platform_device *pdev, void *priv)
 {
 	struct sunxi_priv_data *gmac = priv;
-	int ret;
+	int ret = 0;
 
 	if (gmac->regulator) {
 		ret = regulator_enable(gmac->regulator);
@@ -50,10 +50,12 @@ static int sun7i_gmac_init(struct platform_device *pdev, void *priv)
 		gmac->clk_enabled = 1;
 	} else {
 		clk_set_rate(gmac->tx_clk, SUN7I_GMAC_MII_RATE);
-		clk_prepare(gmac->tx_clk);
+		ret = clk_prepare(gmac->tx_clk);
+		if (ret && gmac->regulator)
+			regulator_disable(gmac->regulator);
 	}
 
-	return 0;
+	return ret;
 }
 
 static void sun7i_gmac_exit(struct platform_device *pdev, void *priv)