lguest: update lazy mmu changes to match lguest's use of kvm hypercalls

Duplicate hcall -> kvm_hypercall0 convertion from "lguest: use KVM
hypercalls".
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Matias Zabaljauregui <zabaljauregui at gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>

arch/x86/lguest/boot.c

@@ -168,7 +168,7 @@ static void lazy_hcall3(unsigned long call,
  * issue the do-nothing hypercall to flush any stored calls. */
 static void lguest_leave_lazy_mmu_mode(void)
 {
-	hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
+	kvm_hypercall0(LHCALL_FLUSH_ASYNC);
 	paravirt_leave_lazy_mmu();
 }