KVM: selftests: Convert vmx_exception_with_invalid_guest_state away from VCPU_ID

Convert vmx_exception_with_invalid_guest_state to use
vm_create_with_one_vcpu() and pass around a 'struct kvm_vcpu' object
instead of using a global VCPU_ID.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>