In the error case, where a power domain cannot be powered on
successfully at boot time (in mtk_register_power_domains),
pm_genpd_init would still be called with is_off=false, and the
system would later try to disable the power domain again, triggering
warnings as disabled clocks are disabled again (and other potential
issues).

Also print a warning splat in that case, as this should never
happen.

Fixes: c84e3587 ("soc: Mediatek: Add SCPSYS power domain driver")
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Link: https://lore.kernel.org/r/20200928113107.v2.1.I5e6f8c262031d0451fe7241b744f4f3111c1ce71@changeidSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>