drm/i915: Apply WaDisableAsyncFlipPerfMode via LRIs on gen8

MI_MODE is saved in the logical context so WaDisableAsyncFlipPerfMode
must be applied using LRIs on gen8.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>