arm/kvm: add support for MTE

arm/kvm: add support for MTE

Extend the 'mte' property for the virt machine to cover KVM as
well. For KVM, we don't allocate tag memory, but instead enable the
capability.

If MTE has been enabled, we need to disable migration, as we do not
yet have a way to migrate the tags as well. Therefore, MTE will stay
off with KVM unless requested explicitly.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230428095533.21747-2-cohuck@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>