hw/arm/virt: introduce DEFINE_VIRT_MACHINE_AS_LATEST

hw/arm/virt: introduce DEFINE_VIRT_MACHINE_AS_LATEST

Create two variants of DEFINE_VIRT_MACHINE. One, just called
DEFINE_VIRT_MACHINE, that does not set properties that only
the latest machine type should have, and another that does.
This will hopefully reduce potential for errors when adding
new versions.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Message-id: 1465746713-30414-4-git-send-email-drjones@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>