drm/i915: WaRsDoubleRc6WrlWithCoarsePowerGating

Cc: Tom O'Rourke <Tom.O'Rourke@intel.com>
Cc: Akash Goel <akash.goel@intel.com>
Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Reviewed-by: Alex Dai <yu.dai@intel.com>
[danvet: Fix continuation alignment.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>