watchdog: ebc-c384_wdt: Utilize devm_ functions in driver probe callback

The devm_ resource manager functions allow memory to be automatically
released when a device is unbound. This patch takes advantage of the
resource manager functions and replaces the watchdog_register_device
call with the devm_watchdog_register_device call. In addition, the
ebc_c384_wdt_remove function has been removed as no longer necessary due
to the use of the relevant devm_ resource manager functions.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>