Drop WaDisablePwrmtrEvent:chv as it's no longer needed.

Also remove the WaSetMaskForGfxBusyness:chv note, but we still
leave the GEN6_RP_MEDIA_IS_GFX bit enabled as that's still the
recommended setting.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>