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 <vidya.srinivas@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 8ed30ab6ac ("drm/i915: Enable YUV to RGB for Gen10 in Plane Ctrl Reg")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180521185613.5097-1-ville.syrjala@linux.intel.com
Reviewed-By: Vidya Srinivas <vidya.srinivas@intel.com>
(cherry picked from commit 012d79e6a3)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -3690,11 +3690,6 @@ u32 glk_plane_color_ctl(const struct intel_crtc_state *crtc_state,
 	plane_color_ctl |= glk_plane_color_ctl_alpha(fb->format->format);
 
 	if (intel_format_is_yuv(fb->format->format)) {
-		if (fb->format->format == DRM_FORMAT_NV12) {
-			plane_color_ctl |=
-				PLANE_COLOR_CSC_MODE_YUV709_TO_RGB709;
-			goto out;
-		}
 		if (plane_state->base.color_encoding == DRM_COLOR_YCBCR_BT709)
 			plane_color_ctl |= PLANE_COLOR_CSC_MODE_YUV709_TO_RGB709;
 		else
@@ -3703,7 +3698,7 @@ u32 glk_plane_color_ctl(const struct intel_crtc_state *crtc_state,
 		if (plane_state->base.color_range == DRM_COLOR_YCBCR_FULL_RANGE)
 			plane_color_ctl |= PLANE_COLOR_YUV_RANGE_CORRECTION_DISABLE;
 	}
-out:
+
 	return plane_color_ctl;
 }