don't UmountDMDevice() in runv
don't UmountDMDevice() in runv

Signed-off-by: Lai Jiangshan <b337eedf453972390e4695e362aeea2634ef4e0c@gmail.com>

wrouesnel/runv,jinfenw/runv,feiskyer/runv,laijs/runv,bergwolf/runv,hyperhq/runv,hyperhq/runv,hyperhq/runv,gao-feng/runv,gnawux/runv,laijs/runv,wrouesnel/runv,bergwolf/runv,gao-feng/runv,jinfenw/runv,gao-feng/runv,gnawux/runv,laijs/runv,gnawux/runv,bergwolf/runv,jinfenw/runv,feiskyer/runv