drm/i915: Simplify platform checks in intel_fb_pitch_limit()

Replace the VLV/CHV check with a HAS_GMCH_DISPLAY check in
intel_fb_pitch_limit(), because it's shorter.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170208175328.11064-1-ville.syrjala@linux.intel.comReviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>

drivers/gpu/drm/i915/intel_display.c

@@ -14346,8 +14346,7 @@ u32 intel_fb_pitch_limit(struct drm_i915_private *dev_priv,
 		 *  pixels and 32K bytes."
 		 */
 		return min(8192 * cpp, 32768);
-	} else if (gen >= 5 && !IS_VALLEYVIEW(dev_priv) &&
-		   !IS_CHERRYVIEW(dev_priv)) {
+	} else if (gen >= 5 && !HAS_GMCH_DISPLAY(dev_priv)) {
 		return 32*1024;
 	} else if (gen >= 4) {
 		if (fb_modifier == I915_FORMAT_MOD_X_TILED)