drm/i915: Allow horizontal mirroring for cnl+ "sprite" planes

All CNL universal planes support horizontal mirroring. Currently
we expose the capability only for the primary plane. Expose it
for the overlay planes as well.

Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181005125817.22576-5-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/intel_sprite.c

@@ -1877,7 +1877,12 @@ intel_sprite_plane_create(struct drm_i915_private *dev_priv,
 		}
 	}
 
-	if (INTEL_GEN(dev_priv) >= 9) {
+	if (INTEL_GEN(dev_priv) >= 10) {
+		supported_rotations =
+			DRM_MODE_ROTATE_0 | DRM_MODE_ROTATE_90 |
+			DRM_MODE_ROTATE_180 | DRM_MODE_ROTATE_270 |
+			DRM_MODE_REFLECT_X;
+	} else if (INTEL_GEN(dev_priv) >= 9) {
 		supported_rotations =
 			DRM_MODE_ROTATE_0 | DRM_MODE_ROTATE_90 |
 			DRM_MODE_ROTATE_180 | DRM_MODE_ROTATE_270;