This patch makes the 2nd DRAM bank available on Juno only and not on
other vexpress64 targets, eg. the FVP models.

The commit below added a 2nd bank of NOR flash for Juno, but also for
all vexpress64 targets:

    commit 2d0cee1c
    Author: Liviu Dudau <Liviu.Dudau@foss.arm.com>
    Date:   Mon Oct 19 11:08:31 2015 +0100

    vexpress64: Juno: Declare all 8GB of RAM and make them visible to the kernel.

    Juno comes with 8GB RAM, but U-Boot only passes 2GB to the kernel.
    Declare a secondary memory bank and set the sizes correctly.

Signed-off-by: Liviu Dudau <Liviu.Dudau@foss.arm.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Ryan Harkin <ryan.harkin@linaro.org>
Tested-by: Ryan Harkin <ryan.harkin@linaro.org>

Unfortunately, I only fully tested on Juno R0, R1 and the FVP Foundation
model.  Whilst FVP Base AEMV8 models run U-Boot OK, they fail to boot
the kernel.

Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
Acked-by: Liviu Dudau <liviu.dudau@foss.arm.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>