video: mxsfb: set gd->fb_base

Set gd->fb_base so it can be shown with bdinfo command.
Signed-off-by: NSébastien Szymanski <sebastien.szymanski@armadeus.com>
Reviewed-by: NPeng Fan <peng.fan@nxp.com>

drivers/video/mxsfb.c

@@ -367,6 +367,7 @@ static int mxs_video_probe(struct udevice *dev)
 	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;
 }