watchdog: imx2_wdt: Drop .remove callback

.remove callback implementation doesn' call clk_disable_unprepare() which
is buggy, actually, we can just use devm_watchdog_register_device() and
devm_add_action_or_reset() to handle all necessary operations for remove
action, then .remove callback can be dropped.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/1582512687-13312-1-git-send-email-Anson.Huang@nxp.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>