dev, arm: Fix incorrect GIC address range sizes

dev, arm: Fix incorrect GIC address range sizes

The GICv2 specifies that 8KiB of the memory map is allocated to the
CPU interface and 4KiB is allocated to the distributor. The current
distributor size is off by 1 and the CPU interface is completely off
by a lot.

Change-Id: I90a9f669a46a37d79c6cc542087cf91f2044f104
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11769