KVM: Fix bogus sign extension in mmu mapping audit

When auditing a 32-bit guest on a 64-bit host, sign extension of the page
table directory pointer table index caused bogus addresses to be shown on
audit errors.

Fix by declaring the index unsigned.
Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/mmu.c

@@ -1360,7 +1360,7 @@ static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte,
 
 static void audit_mappings(struct kvm_vcpu *vcpu)
 {
-	int i;
+	unsigned i;
 
 	if (vcpu->mmu.root_level == 4)
 		audit_mappings_page(vcpu, vcpu->mmu.root_hpa, 0, 4);