watchdog: twl4030_wdt: Convert to use device managed functions and other improvements

Use device managed functions to simplify error handling, reduce
source code size, improve readability, and reduce the likelyhood of bugs.
Other improvements as listed below.

The conversion was done automatically with coccinelle using the
following semantic patches. The semantic patches and the scripts
used to generate this commit log are available at
https://github.com/groeck/coccinelle-patches

- Drop assignments to otherwise unused variables
- Drop empty remove function
- Introduce local variable 'struct device *dev' and use it instead of
  dereferencing it repeatedly
- Use devm_watchdog_register_driver() to register watchdog device
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/twl4030_wdt.c

@@ -70,10 +70,10 @@ static const struct watchdog_ops twl4030_wdt_ops = {
 
 static int twl4030_wdt_probe(struct platform_device *pdev)
 {
-	int ret = 0;
+	struct device *dev = &pdev->dev;
 	struct watchdog_device *wdt;
 
-	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 	if (!wdt)
 		return -ENOMEM;
 
@@ -83,27 +83,14 @@ static int twl4030_wdt_probe(struct platform_device *pdev)
 	wdt->timeout		= 30;
 	wdt->min_timeout	= 1;
 	wdt->max_timeout	= 30;
-	wdt->parent = &pdev->dev;
+	wdt->parent = dev;
 
 	watchdog_set_nowayout(wdt, nowayout);
 	platform_set_drvdata(pdev, wdt);
 
 	twl4030_wdt_stop(wdt);
 
-	ret = watchdog_register_device(wdt);
-	if (ret)
-		return ret;
-
-	return 0;
-}
-
-static int twl4030_wdt_remove(struct platform_device *pdev)
-{
-	struct watchdog_device *wdt = platform_get_drvdata(pdev);
-
-	watchdog_unregister_device(wdt);
-
-	return 0;
+	return devm_watchdog_register_device(dev, wdt);
 }
 
 #ifdef CONFIG_PM
@@ -137,7 +124,6 @@ MODULE_DEVICE_TABLE(of, twl_wdt_of_match);
 
 static struct platform_driver twl4030_wdt_driver = {
 	.probe		= twl4030_wdt_probe,
-	.remove		= twl4030_wdt_remove,
 	.suspend	= twl4030_wdt_suspend,
 	.resume		= twl4030_wdt_resume,
 	.driver		= {