x86: Drop use of global_data fb_base

This value is set by not used on x86 so there is no point in setting it.
Drop the assignment.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/lib/fsp/fsp_graphics.c b/arch/x86/lib/fsp/fsp_graphics.c
index 5f77012..ad25020 100644
--- a/arch/x86/lib/fsp/fsp_graphics.c
+++ b/arch/x86/lib/fsp/fsp_graphics.c
@@ -103,7 +103,6 @@
 	 * For IGD, it seems to be always on BAR2.
 	 */
 	vesa->phys_base_ptr = dm_pci_read_bar32(dev, 2);
-	gd->fb_base = vesa->phys_base_ptr;
 
 	ret = vesa_setup_video_priv(vesa, vesa->phys_base_ptr, uc_priv, plat);
 	if (ret)