watchdog: mtk_wdt: Remove #ifdef guards for PM related functions

Use the new DEFINE_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr() macros to
handle the .suspend/.resume callbacks.

These macros allow the suspend and resume functions to be automatically
dropped by the compiler when CONFIG_SUSPEND is disabled, without having
to use #ifdef guards. Not using #ifdef guards means that the code is
always compiled independently of any Kconfig option, and thanks to that
bugs and regressions are easier to catch.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mediatek@lists.infradead.org
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220628193449.160585-4-paul@crapouillou.net


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