mailbox: sprd: Use devm_clk_get_enabled() helpers

The devm_clk_get_enabled() helpers:
- call devm_clk_get()
- call clk_prepare_enable() and register what is needed in order to
call clk_disable_unprepare() when needed, as a managed resource.

This simplifies the code and avoids the calls to clk_disable_unprepare().

Due to clk only used in probe, not in suspend\resume, this pointer can
remove from sprd_mbox_priv to save a little memory.

Signed-off-by: Huan Yang <[e-mail]>
Reviewed-by: Christophe JAILLET <[e-mail]>
Reviewed-by: Baolin Wang <[e-mail]>
Signed-off-by: Jassi Brar <[e-mail]>

drivers/mailbox/sprd-mailbox.c

···
 	void __iomem		*outbox_base;
 	/*  Base register address for supplementary outbox */
 	void __iomem		*supp_base;
-	struct clk		*clk;
 	u32			outbox_fifo_depth;
 
 	struct mutex		lock;
···
 	.shutdown	= sprd_mbox_shutdown,
 };
 
-static void sprd_mbox_disable(void *data)
-{
-	struct sprd_mbox_priv *priv = data;
-
-	clk_disable_unprepare(priv->clk);
-}
-
 static int sprd_mbox_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct sprd_mbox_priv *priv;
 	int ret, inbox_irq, outbox_irq, supp_irq;
 	unsigned long id, supp;
+	struct clk *clk;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
···
 	if (IS_ERR(priv->outbox_base))
 		return PTR_ERR(priv->outbox_base);
 
-	priv->clk = devm_clk_get(dev, "enable");
-	if (IS_ERR(priv->clk)) {
+	clk = devm_clk_get_enabled(dev, "enable");
+	if (IS_ERR(clk)) {
 		dev_err(dev, "failed to get mailbox clock\n");
-		return PTR_ERR(priv->clk);
-	}
-
-	ret = clk_prepare_enable(priv->clk);
-	if (ret)
-		return ret;
-
-	ret = devm_add_action_or_reset(dev, sprd_mbox_disable, priv);
-	if (ret) {
-		dev_err(dev, "failed to add mailbox disable action\n");
-		return ret;
+		return PTR_ERR(clk);
 	}
 
 	inbox_irq = platform_get_irq_byname(pdev, "inbox");