Input: omap4-keyad - use pm_ptr() and RUNTIME_DEV_PM_OPS()

Input: omap4-keyad - use pm_ptr() and RUNTIME_DEV_PM_OPS()

SET_RUNTIME_DEV_PM_OPS() is deprecated as it requires explicit protection
against unused function warnings.  The new combination of pm_ptr()
and RUNTIME_DEV_PM_OPS() allows the compiler to see the functions,
thus suppressing the warning, but still allowing the unused code to be
removed. Thus also drop the __maybe_unused markings.

Note that DEFINE_RUNTIME_DEV_PM_OPS() is not used because that adds
additional callbacks for suspend and resume and would need
testing.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230114171620.42891-14-jic23@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>