KVM: Use kvm_kvfree() to free memory allocated by kvm_kvzalloc()

The following commit did not care about the error handling path:

  commit c1a7b32a
  KVM: Avoid wasting pages for small lpage_info arrays

If memory allocation fails, vfree() will be called with the address
returned by kzalloc().  This patch fixes this issue.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/x86.c

@@ -6350,7 +6350,7 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 
 out_free:
 	for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i) {
-		vfree(slot->arch.lpage_info[i]);
+		kvm_kvfree(slot->arch.lpage_info[i]);
 		slot->arch.lpage_info[i] = NULL;
 	}
 	return -ENOMEM;