video: fbdev: dnfb: make fb_var_screeninfo static and const

Make this structure static as it is not referenced in any other
file. Make it const as it is used only during a copy operation.
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
[b.zolnierkie: split from combined patch]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

drivers/video/fbdev/dnfb.c

@@ -115,7 +115,7 @@ static struct fb_ops dn_fb_ops = {
 	.fb_imageblit	= cfb_imageblit,
 };
 
-struct fb_var_screeninfo dnfb_var = {
+static const struct fb_var_screeninfo dnfb_var = {
 	.xres		= 1280,
 	.yres		= 1024,
 	.xres_virtual	= 2048,