Replace SET_RUNTIME_PM_OPS() with its modern alternative RUNTIME_PM_OPS().

The combined usage of pm_ptr() and RUNTIME_PM_OPS() allows the
compiler to evaluate if the runtime suspend/resume() functions are used
at build time or are simply dead code.

This allows removing the __maybe_unused notation from the runtime
suspend/resume() functions.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Link: https://msgid.link/r/20240507173735.3456334-1-festevam@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>