dev-arm: modify GICv3 ITS default addr

dev-arm: modify GICv3 ITS default addr

The current default base address for GICv3 ITS stated in RealView is
0x2c120000. The redistributors base address is 0x2c010000; each
instantiated core has an associated redistributor with memory region
size 0x40000 (with GICv4 extension, enabled by default). With 8 cores,
the redistributor range spans to 0x2c210000, creating a conflict with
the ITS address space.

This patch changes the ITS base address to 0x2e010000 which guarantees
no overlapping with the redistributor.

Change-Id: I7dc1af9e69ac037f85ae96f0985554f1fb8372a0
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20608
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>