target/arm/cpu: adjust virtual time for all KVM arm cpus

target/arm/cpu: adjust virtual time for all KVM arm cpus

Virtual time adjustment was implemented for virt-5.0 machine type,
but the cpu property was enabled only for host-passthrough and max
cpu model.  Let's add it for any KVM arm cpu which has the generic
timer feature enabled.

Signed-off-by: Ying Fang <fangying1@huawei.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Message-id: 20200608121243.2076-1-fangying1@huawei.com
[PMM: minor commit message tweak, removed inaccurate
 suggested-by tag]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>