video: Add export.h for THIS_MODULE/EXPORT_SYMBOL to drivers/video

With module.h being implicitly everywhere via device.h, the absence
of explicitly including something for EXPORT_SYMBOL went unnoticed.
Since we are heading to fix things up and clean module.h from the
device.h file, we need to explicitly include these files now.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/video/omap2/dss/rfbi.c b/drivers/video/omap2/dss/rfbi.c
index 1bd3703..1130c60 100644
--- a/drivers/video/omap2/dss/rfbi.c
+++ b/drivers/video/omap2/dss/rfbi.c
@@ -24,6 +24,7 @@
 
 #include <linux/kernel.h>
 #include <linux/dma-mapping.h>
+#include <linux/export.h>
 #include <linux/vmalloc.h>
 #include <linux/clk.h>
 #include <linux/io.h>