net: fec: Switch to RUNTIME/SYSTEM_SLEEP_PM_OPS()

net: fec: Switch to RUNTIME/SYSTEM_SLEEP_PM_OPS()

Replace SET_RUNTIME_PM_OPS()/SET SYSTEM_SLEEP_PM_OPS() with their modern
RUNTIME_PM_OPS() and SYSTEM_SLEEP_PM_OPS() alternatives.

The combined usage of pm_ptr() and RUNTIME_PM_OPS/SYSTEM_SLEEP_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>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Link: https://patch.msgid.link/20240806021628.2524089-1-festevam@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>