drm/radeon/cayman: setup hdp to invalidate and flush when asked

commit 0b65f83f9d2fab47b9b6040fe75fc2cfc73032d4 upstream.

On cayman we need to set the bit to cause HDP flushes to invalidate the
HDP cache also.

Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --cc drivers/gpu/drm/radeon/ni.c
Simple merge

diff --cc drivers/gpu/drm/radeon/nid.h
Simple merge