drm/i915: Force RC6 restore after system resume and reset

drm/i915: Force RC6 restore after system resume and reset

In order for the RC6 autoenable worker to take any action, RC6 first
must be disabled. Upon resume or reset, the sw state may be stale and so
we require a forced restore.

Fixes: 775aca94857d ("drm/i915: Defer enabling rc6 til after we submit...")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160824092701.19178-1-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>