mailbox: imx: Disable the clock on devm_mbox_controller_register() failure

devm_mbox_controller_register() may fail, and in the case of failure the
priv->clk clock that was previously enabled, should be disabled.

Fixes: 2bb70056 ("mailbox: Add support for i.MX messaging unit")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
[Jassi: fixed merge/am conflict]
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/imx-mailbox.c

@@ -513,8 +513,10 @@ static int imx_mu_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, priv);
 
 	ret = devm_mbox_controller_register(dev, &priv->mbox);
-	if (ret)
+	if (ret) {
+		clk_disable_unprepare(priv->clk);
 		return ret;
+	}
 
 	pm_runtime_enable(dev);