hw/arm/virt-acpi-build: Add GICC ACPI subtable for GICv3

When booting VM with GICv3, the kernel needs GICC ACPI subtable to
initialize the CPUs, e.g. MPIDR information. This adds GICC ACPI
subtable for GICv3, but set GICC base address only when gic_version == 2
since it donesn't need GICC base address for GICv3.

Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Message-id: 1446131773-5018-1-git-send-email-shannon.zhao@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>