macintosh/via-pmu: register_pmu_pm_ops() can be __init

register_pmu_pm_ops() is only called at init time, via
device_initcall(), so can be marked __init. The driver can't be built as
a module.

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240821082101.877438-1-mpe@ellerman.id.au