KVM: arm64: selftests: Make vgic_init gic version agnostic

As a preparation for the next commits which will add some tests for
GICv2, make aarch64/vgic_init GIC version agnostic. Add a new generic
run_tests function(gic_dev_type) that starts all applicable tests using
GICv3 or GICv2. GICv2 tests are attempted if GICv3 is not available in
the system. There are currently no GICv2 tests, but the test passes now
in GICv2 systems.
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211005011921.437353-7-ricarkol@google.com