With this patch, virt-3.0 machine uses a new 256MB ECAM region
by default instead of the legacy 16MB one, if highmem is set
(LPAE supported by the guest) and (!firmware_loaded || aarch64).

Indeed aarch32 mode FW may not support this high ECAM region.
Signed-off-by: NEric Auger <eric.auger@redhat.com>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NAndrew Jones <drjones@redhat.com>
Message-id: 1529072910-16156-11-git-send-email-eric.auger@redhat.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>