tools: ARM: vGICv3: Avoid inserting optional DT properties

tools: ARM: vGICv3: Avoid inserting optional DT properties

When creating a GICv3 devicetree node, we currently insert the
redistributor-stride and #redistributor-regions properties, with fixed
values which are actually the architected ones. Since those properties are
optional, and in the case of the stride only needed to cover for broken
platforms, we don't need to describe them if they don't differ from the
default values. This will always be the case for our constructed
DomU memory map.
So we drop those properties altogether and provide a clean and architected
GICv3 DT node for DomUs.

Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>