<fix>[vm]: change maximum vcpu to 240
<fix>[vm]: change maximum vcpu to 240

refer to: https://access.redhat.com/articles/rhel-kvm-limits

Resolves: ZSTAC-45100

Change-Id: I6761686f6e6a6c7078716870746c686677666773

zstackio/zstack-utility,zstackio/zstack-utility,zstackio/zstack-utility