OMAPDSS: add missing export for omap_dss_get_output()

omap_dss_get_output() is a public function, but was missing
EXPORT_SYMBOL().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Archit Taneja <archit@ti.com>
diff --git a/drivers/video/omap2/dss/output.c b/drivers/video/omap2/dss/output.c
index 79dea1a..5214df6 100644
--- a/drivers/video/omap2/dss/output.c
+++ b/drivers/video/omap2/dss/output.c
@@ -113,6 +113,7 @@
 
 	return NULL;
 }
+EXPORT_SYMBOL(omap_dss_get_output);
 
 static const struct dss_mgr_ops *dss_mgr_ops;