net: bcmgenet: Use devm_clk_get_optional() to get the clocks

Conversion to devm_clk_get_optional() makes it explicit that clocks are
optional. This change allows to handle deferred probe in case clocks are
defined, but not yet probed. Due to above changes bail out in error case.

While here, check potential error when enable main clock.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmgenet.c

@@ -3487,13 +3487,16 @@ static int bcmgenet_probe(struct platform_device *pdev)
 		priv->dma_max_burst_length = DMA_MAX_BURST_LENGTH;
 	}
 
-	priv->clk = devm_clk_get(&priv->pdev->dev, "enet");
+	priv->clk = devm_clk_get_optional(&priv->pdev->dev, "enet");
 	if (IS_ERR(priv->clk)) {
 		dev_dbg(&priv->pdev->dev, "failed to get enet clock\n");
-		priv->clk = NULL;
+		err = PTR_ERR(priv->clk);
+		goto err;
 	}
 
-	clk_prepare_enable(priv->clk);
+	err = clk_prepare_enable(priv->clk);
+	if (err)
+		goto err;
 
 	bcmgenet_set_hw_params(priv);
 
@@ -3511,16 +3514,18 @@ static int bcmgenet_probe(struct platform_device *pdev)
 	priv->rx_buf_len = RX_BUF_LENGTH;
 	INIT_WORK(&priv->bcmgenet_irq_work, bcmgenet_irq_task);
 
-	priv->clk_wol = devm_clk_get(&priv->pdev->dev, "enet-wol");
+	priv->clk_wol = devm_clk_get_optional(&priv->pdev->dev, "enet-wol");
 	if (IS_ERR(priv->clk_wol)) {
 		dev_dbg(&priv->pdev->dev, "failed to get enet-wol clock\n");
-		priv->clk_wol = NULL;
+		err = PTR_ERR(priv->clk_wol);
+		goto err;
 	}
 
-	priv->clk_eee = devm_clk_get(&priv->pdev->dev, "enet-eee");
+	priv->clk_eee = devm_clk_get_optional(&priv->pdev->dev, "enet-eee");
 	if (IS_ERR(priv->clk_eee)) {
 		dev_dbg(&priv->pdev->dev, "failed to get enet-eee clock\n");
-		priv->clk_eee = NULL;
+		err = PTR_ERR(priv->clk_eee);
+		goto err;
 	}
 
 	/* If this is an internal GPHY, power it on now, before UniMAC is