soc: dove: Let genpd deal with disabling of unused PM domains

Genpd tries from a late_initcall to disable unused PM domains, which makes
it unnecessary to also manage this from any earlier phase when for example
initializing a genpd.

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