KVM: MMU: use kvm_sync_page in kvm_sync_pages

If the last argument is true, kvm_unlink_unsync_page is called anyway in
__kvm_sync_page (either by kvm_mmu_prepare_zap_page or by __kvm_sync_page
itself).  Therefore, kvm_sync_pages can just call kvm_sync_page, instead
of going through kvm_unlink_unsync_page+__kvm_sync_page.
Reviewed-by: NTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -1987,8 +1987,7 @@ static void kvm_sync_pages(struct kvm_vcpu *vcpu,  gfn_t gfn)
 			continue;
 
 		WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
-		kvm_unlink_unsync_page(vcpu->kvm, s);
-		if (!__kvm_sync_page(vcpu, s, &invalid_list, false))
+		if (!kvm_sync_page(vcpu, s, &invalid_list))
 			flush = true;
 	}