kvm: kvm_destroy_vm_debugfs(): check debugfs_stat_data pointer

This make it possible to call kvm_destroy_vm_debugfs() from
kvm_create_vm_debugfs() in error conditions.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

virt/kvm/kvm_main.c

@@ -559,9 +559,11 @@ static void kvm_destroy_vm_debugfs(struct kvm *kvm)
 
 	debugfs_remove_recursive(kvm->debugfs_dentry);
 
-	for (i = 0; i < kvm_debugfs_num_entries; i++)
-		kfree(kvm->debugfs_stat_data[i]);
-	kfree(kvm->debugfs_stat_data);
+	if (kvm->debugfs_stat_data) {
+		for (i = 0; i < kvm_debugfs_num_entries; i++)
+			kfree(kvm->debugfs_stat_data[i]);
+		kfree(kvm->debugfs_stat_data);
+	}
 }
 
 static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)