platform/x86: amd: pmc: Remove __maybe_unused from amd_pmc_suspend_handler()

Now that the pmc code has switched to DEFINE_SIMPLE_DEV_PM_OPS()
the __maybe_unused is no longer necessary, drop it.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20230410193512.64232-1-hdegoede@redhat.com