virt-test: run cpuid.custom variants without kvm

cpuid.custom will fail if qemu is built without kvm,
due to virt-test tries to start qemu in kvm mode.

To fix it run custom variants in TCG mode, since they do
not have anything kvm specific.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>

qemu/tests/cfg/qemu_cpu.cfg

@@ -51,6 +51,7 @@
                                     cpu_models += " cpu64-rhel6 cpu64-rhel5"
         # CPUID data tests:
         - cpuid.custom:
+            disable_kvm = yes
             variants:
                 - vendor:
                     test_type = "custom_vendor"