net: ethernet: arc: fix error handling in emac_rockchip_probe

If clk_set_rate() fails, we should disable clk before return.
Found by Linux Driver Verification project (linuxtesting.org).

Changes since v2 [1]:
* Merged with latest code changes

Changes since v1:
Update made thanks to David's review, much appreciated David.
* Improved inconsistent failure handling of clock rate setting
* For completeness of usecase, added arc_emac_probe error handling

Signed-off-by: Branislav Radocaj <branislav@radocaj.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/arc/emac_rockchip.c

@@ -199,9 +199,11 @@ static int emac_rockchip_probe(struct platform_device *pdev)
 
 	/* RMII interface needs always a rate of 50MHz */
 	err = clk_set_rate(priv->refclk, 50000000);
-	if (err)
+	if (err) {
 		dev_err(dev,
 			"failed to change reference clock rate (%d)\n", err);
+		goto out_regulator_disable;
+	}
 
 	if (priv->soc_data->need_div_macclk) {
 		priv->macclk = devm_clk_get(dev, "macclk");
@@ -230,12 +232,14 @@ static int emac_rockchip_probe(struct platform_device *pdev)
 	err = arc_emac_probe(ndev, interface);
 	if (err) {
 		dev_err(dev, "failed to probe arc emac (%d)\n", err);
-		goto out_regulator_disable;
+		goto out_clk_disable_macclk;
 	}
 
 	return 0;
+
 out_clk_disable_macclk:
-	clk_disable_unprepare(priv->macclk);
+	if (priv->soc_data->need_div_macclk)
+		clk_disable_unprepare(priv->macclk);
 out_regulator_disable:
 	if (priv->regulator)
 		regulator_disable(priv->regulator);