drm/i915/gen11: Expose planar format support on gen11, v2.

Now that we implemented support for planar formats on gen11, we can
finally advertise it.

Changes since v1:
- Re-add change to skl_plane_has_planar(), was lost in rebase noise.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181022134514.14756-1-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/intel_display.c

@@ -14516,7 +14516,7 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb,
 		break;
 	case DRM_FORMAT_NV12:
 		if (INTEL_GEN(dev_priv) < 9 || IS_SKYLAKE(dev_priv) ||
-		    IS_BROXTON(dev_priv) || INTEL_GEN(dev_priv) >= 11) {
+		    IS_BROXTON(dev_priv)) {
 			DRM_DEBUG_KMS("unsupported pixel format: %s\n",
 				      drm_get_format_name(mode_cmd->pixel_format,
 							  &format_name));

drivers/gpu/drm/i915/intel_sprite.c

@@ -1863,12 +1863,8 @@ static bool skl_plane_has_fbc(struct drm_i915_private *dev_priv,
 static bool skl_plane_has_planar(struct drm_i915_private *dev_priv,
 				 enum pipe pipe, enum plane_id plane_id)
 {
-	/*
-	 * FIXME: ICL requires two hardware planes for scanning out NV12
-	 * framebuffers. Do not advertize support until this is implemented.
-	 */
 	if (INTEL_GEN(dev_priv) >= 11)
-		return false;
+		return plane_id <= PLANE_SPRITE3;
 
 	if (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv))
 		return false;