PM / devfreq: exynos: Use DEFINE_SIMPLE_DEV_PM_OPS for PM functions

This macro has the advantage over SET_SYSTEM_SLEEP_PM_OPS that we don't
have to care about when the functions are actually used.

Also make use of pm_sleep_ptr() to discard all PM_SLEEP related
stuff if CONFIG_PM_SLEEP isn't enabled.

Link: https://lore.kernel.org/lkml/20240417044459.1908-2-linux.amoon@gmail.com/


Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>