KVM: nVMX: Drop the SMP configuration of the ST APIC passthrough test

The APIC passthrough test has single-thread and dual-threaded variants.
Drop the testcase that runs the single-threaded variant with smp=2, it
provides no additional value over running the test in the generic "vmx"
testcase.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>