hwrng: rockchip - handle devm_pm_runtime_enable errors

It's unlikely that devm_pm_runtime_enable ever fails. Still, it makes
sense to read the return value and handle errors.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/rockchip-rng.c

@@ -169,7 +169,9 @@ static int rk_rng_probe(struct platform_device *pdev)
 
 	pm_runtime_set_autosuspend_delay(dev, RK_RNG_AUTOSUSPEND_DELAY);
 	pm_runtime_use_autosuspend(dev);
-	devm_pm_runtime_enable(dev);
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "Runtime pm activation failed.\n");
 
 	ret = devm_hwrng_register(dev, &rk_rng->rng);
 	if (ret)