drm/i915/chv: Implement WaDisableSemaphoreAndSyncFlipWait:chv

BDW has the same requirement but the w/a database doens't list
this w/a for BDW. Seems to be another one of those "stick a bunch
of known workarounds into this bag and write something on the label"
type of things.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>