video: mxsfb: set gd->fb_base

Set gd->fb_base so it can be shown with bdinfo command.

Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
index 6922a13..c529810 100644
--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -367,6 +367,7 @@
 	mmu_set_region_dcache_behaviour(fb_start, fb_end - fb_start,
 					DCACHE_WRITEBACK);
 	video_set_flush_dcache(dev, true);
+	gd->fb_base = plat->base;
 
 	return ret;
 }