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 <link@vivo.com>
Reviewed-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>

drivers/mailbox/sprd-mailbox.c

@@ -62,7 +62,6 @@ struct sprd_mbox_priv {
  void __iomem *outbox_base;
  /* Base register address for supplementary outbox */
  void __iomem *supp_base;
- struct clk *clk;
  u32 outbox_fifo_depth;
 
  struct mutex lock;
@@ -291,19 +290,13 @@ static const struct mbox_chan_ops sprd_mbox_ops = {
  .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)
@@ -331,20 +324,10 @@ static int sprd_mbox_probe(struct platform_device *pdev)
  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");