watchdog: s3c2410_wdt: use dev_err()/dev_info() instead of pr_err()/pr_info()

dev_err()/dev_info() are more preferred than pr_err()/pr_info().

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>