PM / domains: Add late_initcall to disable unused PM domains

As default behavior let genpd at late init try to disable the unused
PM domains.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>