dev-arm,system-arm: missing GICv3 ranges property

dev-arm,system-arm: missing GICv3 ranges property

This patch adds the device tree "ranges" property to GICv3 for
the VExpress_GEM5_V2 platform. It is also included in the GICv3 DTB
auto generation.
This allows the GICv3 ITS to be specified in the device tree.

Change-Id: I00e1bb0fd45521e34820c0a23ddf047afec7aa4c
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20255
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>