drm/i915: Enabling RC6 where possible

Ok, here's a "final" patch set to enable RC6 where possible on SNB and IVB machines. The first patch creates a new variable, intel_iommu_enabled, that is exported by the intel iommu code and set when that code has successfully initialized itself. The old plan of using no_iommu || dmar_disabled

drm/i915: Enabling RC6 where possible

Ok, here's a final patch set to enable RC6 where possible on SNB and IVB machines. The first patch creates a new variable, intel_iommu_enabled, that is exported by the intel iommu code and set when that code has successfully initialized itself. The old plan of using no_iommu || dmar_disabled