hwrng: drivers - Use device-managed registration API

Use devm_hwrng_register to simplify the implementation.
Manual unregistration and some remove functions can be
removed now.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Acked-by: Łukasz Stelmach <l.stelmach@samsung.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/atmel-rng.c

@@ -86,7 +86,7 @@ static int atmel_trng_probe(struct platform_device *pdev)
 	trng->rng.name = pdev->name;
 	trng->rng.read = atmel_trng_read;
 
-	ret = hwrng_register(&trng->rng);
+	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
 	if (ret)
 		goto err_register;
 
@@ -103,7 +103,6 @@ static int atmel_trng_remove(struct platform_device *pdev)
 {
 	struct atmel_trng *trng = platform_get_drvdata(pdev);
 
-	hwrng_unregister(&trng->rng);
 
 	atmel_trng_disable(trng);
 	clk_disable_unprepare(trng->clk);