OMAPDSS: split overlay sysfs code

Separate sysfs code for overlays to a separate file. This is a bit
cleaner, and will allow us later to easily switch off the sysfs support
via Kconfig option.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dss.h b/drivers/video/omap2/dss/dss.h
index d6cca82..11b053e 100644
--- a/drivers/video/omap2/dss/dss.h
+++ b/drivers/video/omap2/dss/dss.h
@@ -265,6 +265,9 @@
 		const struct omap_video_timings *mgr_timings);
 bool dss_ovl_use_replication(struct dss_lcd_mgr_config config,
 		enum omap_color_mode mode);
+int dss_overlay_kobj_init(struct omap_overlay *ovl,
+		struct platform_device *pdev);
+void dss_overlay_kobj_uninit(struct omap_overlay *ovl);
 
 /* DSS */
 int dss_init_platform_driver(void) __init;