KVM: x86: Fix posted interrupt with CONFIG_SMP=n

->send_IPI_mask is not defined on UP.
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/vmx.c

@@ -3946,10 +3946,12 @@ static void vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
 
 	r = pi_test_and_set_on(&vmx->pi_desc);
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
+#ifdef CONFIG_SMP
 	if (!r && (vcpu->mode == IN_GUEST_MODE))
 		apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
 				POSTED_INTR_VECTOR);
 	else
+#endif
 		kvm_vcpu_kick(vcpu);
 }