x86: Gracefully disable the vesa driver when running from EFI

x86: Gracefully disable the vesa driver when running from EFI

We cannot use this driver when running from EFI as we have no direct hardware
access. In fact coreboot uses a different driver which uses tables provided
by coreboot. So far it does not seem possible to use a normal video driver
when booting from EFI.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Anatolij Gustschin <agust@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>