numad_vcpupin: skip cpu not pin

[dzhengfy]

There are some host cpus which can not be pin by default. Original codes did not test those cpus and directly pin to those host cpus which causes similar error like below:

error: Unable to write to '/sys/fs/cgroup/cpuset/machine.slice/ machine-qemu\x2d1\x2davocado\x2dvt\x2dvm1.scope/libvirt/ vcpu0/cpuset.cpus': Permission denied

So we need to skip those cpus when testing vcpupin.

Depends on https://github.com/avocado-framework/avocado-vt/pull/3389 Signed-off-by: Dan Zheng [email protected]