KVM: arm64: selftests: Add support for GICv2 on v3

The current vgic_init test wrongly assumes that the host cannot
multiple versions of the GIC architecture, while v2 emulation
on v3 has almost always been supported (it was supported before
the standalone v3 emulation).

Tweak the test to support multiple GIC incarnations.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Fixes: 3f4db37e ("KVM: arm64: selftests: Make vgic_init gic version agnostic")
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Link: https://lore.kernel.org/r/20220714154108.3531213-1-maz@kernel.org