hwrng: imx-rngc - use devres for hwrng registration

Replace hwrng_register with devm_hwrng_register and let devres unregister
our hwrng when the device is removed.

It's possible to do this now that devres also handles clock
disable+uprepare. When we had to disable+unprepare the clock ourselves,
we had to unregister the hwrng before this and couldn't use devres.

There's nothing left to do for imx_rngc_remove, this function can go.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/imx-rngc.c

@@ -292,7 +292,7 @@ static int imx_rngc_probe(struct platform_device *pdev)
 		}
 	}
 
-	ret = hwrng_register(&rngc->rng);
+	ret = devm_hwrng_register(&pdev->dev, &rngc->rng);
 	if (ret) {
 		dev_err(&pdev->dev, "hwrng registration failed\n");
 		return ret;
@@ -305,15 +305,6 @@ static int imx_rngc_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static int __exit imx_rngc_remove(struct platform_device *pdev)
-{
-	struct imx_rngc *rngc = platform_get_drvdata(pdev);
-
-	hwrng_unregister(&rngc->rng);
-
-	return 0;
-}
-
 static int __maybe_unused imx_rngc_suspend(struct device *dev)
 {
 	struct imx_rngc *rngc = dev_get_drvdata(dev);
@@ -346,7 +337,6 @@ static struct platform_driver imx_rngc_driver = {
 		.pm = &imx_rngc_pm_ops,
 		.of_match_table = imx_rngc_dt_ids,
 	},
-	.remove = __exit_p(imx_rngc_remove),
 };
 
 module_platform_driver_probe(imx_rngc_driver, imx_rngc_probe);