clocksource/drivers/ingenic-ost: Define pm functions properly in platform_driver struct

Commit ca7b72b5 ("clocksource: Add driver for the Ingenic JZ47xx OST")
adds the struct platform_driver ingenic_ost_driver, with the definition of
pm functions under the non-existing config PM_SUSPEND, which means the
intended pm functions were never actually included in any build.

As the only callbacks are .suspend_noirq and .resume_noirq, we can assume
that it is intended to be CONFIG_PM_SLEEP.

Since commit 1a3c7bb0 ("PM: core: Add new *_PM_OPS macros, deprecate
old ones"), the default pattern for platform_driver definitions
conditional for CONFIG_PM_SLEEP is to use pm_sleep_ptr().

As __maybe_unused annotations on the dev_pm_ops structure and its callbacks
are not needed anymore, remove these as well.

Suggested-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20221123083159.22821-1-lukas.bulwahn@gmail.com