video: fbdev: xilinxfb: constify copied structure

Make const xilinx_fb_default_pdata structure that is only copied into
other structure.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Soren Brinkmann <soren.brinkmann@xilinx.com>,
[b.zolnierkie: split from a bigger patch]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

drivers/video/fbdev/xilinxfb.c

@@ -100,7 +100,7 @@ struct xilinxfb_platform_data {
 /*
  * Default xilinxfb configuration
  */
-static struct xilinxfb_platform_data xilinx_fb_default_pdata = {
+static const struct xilinxfb_platform_data xilinx_fb_default_pdata = {
 	.xres = 640,
 	.yres = 480,
 	.xvirt = 1024,