drm/i915: Move LUT programming to happen after vblank waits

drm/i915: Move LUT programming to happen after vblank waits

The LUTs are single buffered so we should program them after
the double buffered pipe updates have been latched by the
hardware.

We'll also fix up the IPS vs. split gamma w/a to do the IPS
disable like everyone else. Note that this is currently dead
code as we don't use the split gamma mode on HSW, but that
will be fixed up shortly.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190205160848.24662-7-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>