clocksource/drivers/timer-ti-dm: Convert to devm_platform_ioremap_resource

Use devm_platform_ioremap_resource() to simplify code, which
wraps 'platform_get_resource' and 'devm_ioremap_resource' in a
single helper.
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20191221173027.30716-4-tiny.windzz@gmail.com

drivers/clocksource/timer-ti-dm.c

@@ -780,7 +780,7 @@ static int omap_dm_timer_probe(struct platform_device *pdev)
 {
 	unsigned long flags;
 	struct omap_dm_timer *timer;
-	struct resource *mem, *irq;
+	struct resource *irq;
 	struct device *dev = &pdev->dev;
 	const struct dmtimer_platform_data *pdata;
 	int ret;
@@ -802,18 +802,12 @@ static int omap_dm_timer_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (unlikely(!mem)) {
-		dev_err(dev, "%s: no memory resource.\n", __func__);
-		return -ENODEV;
-	}
-
 	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
 	if (!timer)
 		return  -ENOMEM;
 
 	timer->fclk = ERR_PTR(-ENODEV);
-	timer->io_base = devm_ioremap_resource(dev, mem);
+	timer->io_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(timer->io_base))
 		return PTR_ERR(timer->io_base);