drm/i915: rename intel_power_domains_resume to *_sync_hw

Give a more proper name to this function.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446657859-9598-5-git-send-email-imre.deak@intel.com