iio: adc: rockchip_saradc: replace custom logic with devm_reset_control_get_optional_exclusive

devm_reset_control_get_optional_exclusive does what this driver is
trying to do in its probe function, therefore let's switch over to that
subsystem function.

Signed-off-by: Quentin Schulz <[e-mail]>
Reviewed-by: Heiko Stuebner <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/rockchip_saradc.c

···
 	 * The reset should be an optional property, as it should work
 	 * with old devicetrees as well
 	 */
-	info->reset = devm_reset_control_get_exclusive(&pdev->dev,
-						       "saradc-apb");
+	info->reset = devm_reset_control_get_optional_exclusive(&pdev->dev,
+								"saradc-apb");
 	if (IS_ERR(info->reset)) {
 		ret = PTR_ERR(info->reset);
-		if (ret != -ENOENT)
-			return dev_err_probe(&pdev->dev, ret,
-					     "failed to get saradc-apb\n");
-
-		dev_dbg(&pdev->dev, "no reset control found\n");
-		info->reset = NULL;
+		return dev_err_probe(&pdev->dev, ret, "failed to get saradc-apb\n");
 	}
 
 	init_completion(&info->completion);