drm/i915: Unify skylake plane update

Don't handle skylake primary plane separately as it is similar
plane as the others.

Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1508270891-22186-4-git-send-email-juhapekka.heikkila@gmail.com
diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 86fc9b5..c3583dc 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -230,7 +230,7 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state)
 #endif
 }
 
-static void
+void
 skl_update_plane(struct intel_plane *plane,
 		 const struct intel_crtc_state *crtc_state,
 		 const struct intel_plane_state *plane_state)