mailbox: arm-mhu: Use device-managed registration API

Get rid of some boilerplate driver removal code by using the newly added
device-managed registration API.
Reviewed-by: NSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NJassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/arm_mhu.c

@@ -152,7 +152,7 @@ static int mhu_probe(struct amba_device *adev, const struct amba_id *id)
 
 	amba_set_drvdata(adev, mhu);
 
-	err = mbox_controller_register(&mhu->mbox);
+	err = devm_mbox_controller_register(dev, &mhu->mbox);
 	if (err) {
 		dev_err(dev, "Failed to register mailboxes %d\n", err);
 		return err;
@@ -162,15 +162,6 @@ static int mhu_probe(struct amba_device *adev, const struct amba_id *id)
 	return 0;
 }
 
-static int mhu_remove(struct amba_device *adev)
-{
-	struct arm_mhu *mhu = amba_get_drvdata(adev);
-
-	mbox_controller_unregister(&mhu->mbox);
-
-	return 0;
-}
-
 static struct amba_id mhu_ids[] = {
 	{
 		.id	= 0x1bb098,
@@ -186,7 +177,6 @@ static struct amba_driver arm_mhu_driver = {
 	},
 	.id_table	= mhu_ids,
 	.probe		= mhu_probe,
-	.remove		= mhu_remove,
 };
 module_amba_driver(arm_mhu_driver);