drm/i915: Remove bogus NV12 PLANE_COLOR_CTL setup

drm/i915: Remove bogus NV12 PLANE_COLOR_CTL setup

We already handle the color encoding mode properly. Remove the broken
NV12 special case.

Cc: Vidya Srinivas <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Fixes: 8ed30ab6aced ("drm/i915: Enable YUV to RGB for Gen10 in Plane Ctrl Reg")
Signed-off-by: Ville Syrjälä <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Reviewed-By: Vidya Srinivas <[email protected]>
(cherry picked from commit 012d79e6a33f095c293fe2a02b2b3b26d8c6402c)
Signed-off-by: Jani Nikula <[email protected]>