mfd: ti_am335x_tscadc: Use devm_ioremap_resource()

Use devm_ioremap_resource() in order to make the code simpler,
and remove redundant return value check of platform_get_resource()
because the value is checked by devm_ioremap_resource().
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/ti_am335x_tscadc.c

@@ -183,12 +183,6 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res) {
-		dev_err(&pdev->dev, "no memory resource defined.\n");
-		return -EINVAL;
-	}
-
 	/* Allocate memory for device */
 	tscadc = devm_kzalloc(&pdev->dev,
 			sizeof(struct ti_tscadc_dev), GFP_KERNEL);
@@ -205,19 +199,10 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 	} else
 		tscadc->irq = err;
 
-	res = devm_request_mem_region(&pdev->dev,
-			res->start, resource_size(res), pdev->name);
-	if (!res) {
-		dev_err(&pdev->dev, "failed to reserve registers.\n");
-		return -EBUSY;
-	}
-
-	tscadc->tscadc_base = devm_ioremap(&pdev->dev,
-			res->start, resource_size(res));
-	if (!tscadc->tscadc_base) {
-		dev_err(&pdev->dev, "failed to map registers.\n");
-		return -ENOMEM;
-	}
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	tscadc->tscadc_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(tscadc->tscadc_base))
+		return PTR_ERR(tscadc->tscadc_base);
 
 	tscadc->regmap_tscadc = devm_regmap_init_mmio(&pdev->dev,
 			tscadc->tscadc_base, &tscadc_regmap_config);