This patch drops the vtimer virtual timer adjust, cross version migration
from openEuler qemu-4.0.1 to qemu-4.1.0 is not supported as a consequence.
By default openEuler qemu-4.1.0 use kvm_adjvtime as the virtual timer.
Signed-off-by: Ying Fang <fangying1@huawei.com>
