KVM: arm/arm64: move GICv2 emulation defines into arm-gic-v3.h

As (some) GICv3 hosts can emulate a GICv2, some GICv2 specific masks
for the list register definition also apply to GICv3 LRs.
At the moment we have those definitions in the KVM VGICv3
implementation, so let's move them into the GICv3 header file to
have them automatically defined.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>