video: mxs: Avoid setting global_data fb_base

This is not used, so don't set it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
index 792d631..e72839c 100644
--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -335,7 +335,6 @@
 	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;
 }