PM: domains: Drop genpd status manipulation for hibernate restore

The genpd status manipulation for hibernate restore has really never
worked as intended.  For example, if the genpd->status was GENPD_STATE_ON,
the parent domain's `sd_count` must have been increased, so it needs to
be adjusted too.  So drop this status manipulation.

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