fixup! drm/xe/display: Implement display support

drm/xe: Fixup small bug in xe_de.h

In display it's not called from irq context, so use xe_mmio_wait32 with
atomic = false. This fixes a splat and the need for i915_utils.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Closes: #245