Merge tag 'drm-intel-next-2019-04-04' into gvt-next

Merge back drm-intel-next for engine name definition refinement
and 54939ea0 ("drm/i915: Switch to use HWS indices rather than addresses")
that would need gvt fixes to depend on.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>