drm/sun4i: Pass modifier to backend and frontend format support helpers

To prepare the introduction of tiled mode support, pass the framebuffer
format modifier to the helpers dealing with format support.

Since only linear mode is supported for now, add corresponding checks in
each helper.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181123092515.2511-33-paul.kocialkowski@bootlin.com

drivers/gpu/drm/sun4i/sun4i_frontend.h

@@ -97,6 +97,6 @@ void sun4i_frontend_update_coord(struct sun4i_frontend *frontend,
 				 struct drm_plane *plane);
 int sun4i_frontend_update_formats(struct sun4i_frontend *frontend,
 				  struct drm_plane *plane, uint32_t out_fmt);
-bool sun4i_frontend_format_is_supported(uint32_t fmt);
+bool sun4i_frontend_format_is_supported(uint32_t fmt, uint64_t modifier);
 
 #endif /* _SUN4I_FRONTEND_H_ */