fix maxvcpu increase makes the case checking maxvcpu failed

[nanli1]

Update two cases

• ioapic_iommu case: maxvxpu num changes from 710 to 2096
• no_iommu case: automatically configure iommu (if it is missing) in the right way if a user
  requests >255 CPUs. Source defect xxxx -65844 - this would be positive scenario , because the ioapic would be added automatically

Signed-off-by: nanli [email protected]

Before fixed

 avocado run --vt-type libvirt --vt-omit-data-loss --vt-machine-type q35 max_vcpus.negative_test.ioapic_iommu --vt-connect-uri qemu:///system

 (1/1) type_specific.io-github-autotest-libvirt.max_vcpus.negative_test.ioapic_iommu: FAIL: Expect should fail with one of unsupported configuration: Maximum CPUs greater than specified machine type limit|exceeds the maximum cpus supported, but succeeded: Domain 'avocado-vt-vm1' defined from /var/tmp/xml_utils_temp_7kyym6dk.xml\n\n\n (6.16 s)

avocado run --vt-type libvirt --vt-omit-data-loss --vt-machine-type q35 max_vcpus.negative_test.no_iommu --vt-connect-uri qemu:///system
 (1/1) type_specific.io-github-autotest-libvirt.max_vcpus.negative_test.no_iommu: FAIL: Expect should fail with one of unsupported configuration: more than 255 vCPUs require extended interrupt mode enabled on the iommu device, but succeeded: Domain 'avocado-vt-vm1' defined from /var/tmp/xml_utils_temp_v5iyoaqy.xml\n\n\n (8.07 s)

After fixed

 avocado run --vt-type libvirt --vt-omit-data-loss --vt-machine-type q35 max_vcpus.negative_test.ioapic_iommu --vt-connect-uri qemu:///system

 (1/1) type_specific.io-github-autotest-libvirt.max_vcpus.negative_test.ioapic_iommu: PASS (5.92 s)

avocado run --vt-type libvirt --vt-omit-data-loss --vt-machine-type q35 max_vcpus.negative_test.no_iommu --vt-connect-uri qemu:///system
 (1/1) type_specific.io-github-autotest-libvirt.max_vcpus.negative_test.no_iommu: FAIL: Expect should succeed, but got: \n\nerror: Failed to define domain from /var/tmp/xml_utils_temp_almayp_e.xml\nerror: unsupported configuration: IOMMU interrupt remapping requires split I/O APIC (ioapic driver='qemu')\n (14.29 s)
this Would be PASS after bug xxxx-65844 fixed