mailbox: sti: Use device-managed registration API

Get rid of some boilerplate driver removal code by using the newly added
device-managed registration API.

Acked-by: Lee Jones <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>
Signed-off-by: Jassi Brar <[e-mail]>

drivers/mailbox/mailbox-sti.c

···
 	mbox->chans		= chans;
 	mbox->num_chans		= STI_MBOX_CHAN_MAX;
 
-	ret = mbox_controller_register(mbox);
+	ret = devm_mbox_controller_register(&pdev->dev, mbox);
 	if (ret)
 		return ret;
 
···
 					IRQF_ONESHOT, mdev->name, mdev);
 	if (ret) {
 		dev_err(&pdev->dev, "Can't claim IRQ %d\n", irq);
-		mbox_controller_unregister(mbox);
 		return -EINVAL;
 	}
 
···
 	return 0;
 }
 
-static int sti_mbox_remove(struct platform_device *pdev)
-{
-	struct sti_mbox_device *mdev = platform_get_drvdata(pdev);
-
-	mbox_controller_unregister(mdev->mbox);
-
-	return 0;
-}
-
 static struct platform_driver sti_mbox_driver = {
 	.probe = sti_mbox_probe,
-	.remove = sti_mbox_remove,
 	.driver = {
 		.name = "sti-mailbox",
 		.of_match_table = sti_mailbox_match,