arm64: vexpress: Add CLCD support to the ARMv8 model platform

This patch enables CLCD support for the VE platform emulated by the
ARMv8 software model (DT bindings are based on Pawel's vexpress
patches) together with defconfig entries for SERIO_AMBAKMI and
FB_ARMCLCD.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>