power_domain: gpio: use on-off and startup time

Respect the configured values for how long the domain takes to turn on,
and how long the domain needs to be off for before it can be repowered.

As these actions can block, guard the transition function with
pm_device_action_can_block. To avoid system PM being able to turn the
domain off but not back on again, guard the entire implementation.

Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>