soc: mediatek: pm-domains: Don't print an error if child domain is deferred

soc: mediatek: pm-domains: Don't print an error if child domain is deferred

Child domains can be deferred by the core because one of its resources
is not available yet, in such case, it will print an error, but
later it will succeed to probe. Fix that using the dev_err_probe()
function so it only prints an error on a real error.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org>
Link: https://lore.kernel.org/r/20210113213012.67643-1-enric.balletbo@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>