drm/i915: Simplify DP port limited color range bit platform checks

Instead of checking for everything not supporting the limited color
range bit in the DP port register, let's check for the one thing
that does have it (g4x).

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jim Bride <jim.bride@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479145447-12907-3-git-send-email-ville.syrjala@linux.intel.com
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 56431e0..a1b0181 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1791,9 +1791,7 @@ static void intel_dp_prepare(struct intel_encoder *encoder,
 			trans_dp &= ~TRANS_DP_ENH_FRAMING;
 		I915_WRITE(TRANS_DP_CTL(crtc->pipe), trans_dp);
 	} else {
-		if (!HAS_PCH_SPLIT(dev_priv) && !IS_VALLEYVIEW(dev_priv) &&
-		    !IS_CHERRYVIEW(dev_priv) &&
-		    pipe_config->limited_color_range)
+		if (IS_G4X(dev_priv) && pipe_config->limited_color_range)
 			intel_dp->DP |= DP_COLOR_RANGE_16_235;
 
 		if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
@@ -2515,8 +2513,7 @@ static void intel_dp_get_config(struct intel_encoder *encoder,
 
 	pipe_config->base.adjusted_mode.flags |= flags;
 
-	if (!HAS_PCH_SPLIT(dev_priv) && !IS_VALLEYVIEW(dev_priv) &&
-	    !IS_CHERRYVIEW(dev_priv) && tmp & DP_COLOR_RANGE_16_235)
+	if (IS_G4X(dev_priv) && tmp & DP_COLOR_RANGE_16_235)
 		pipe_config->limited_color_range = true;
 
 	pipe_config->lane_count =