i.MX: ipufb: add const to fb_videomode declarations

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
diff --git a/board/freescale/mx51evk/mx51evk.c b/board/freescale/mx51evk/mx51evk.c
index 3412952..421d8c2 100644
--- a/board/freescale/mx51evk/mx51evk.c
+++ b/board/freescale/mx51evk/mx51evk.c
@@ -471,7 +471,7 @@
 }
 #endif
 
-static struct fb_videomode claa_wvga = {
+static struct fb_videomode const claa_wvga = {
 	.name		= "CLAA07LC0ACW",
 	.refresh	= 57,
 	.xres		= 800,