Bluetooth: mgmt: Fix the command returns garbage parameter value

When the Get Device Flags command fails, it returns the error status
with the parameters filled with the garbage values. Although the
parameters are not used, it is better to fill with zero than the random
values.
Signed-off-by: NTedd Ho-Jeong An <tedd.an@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/bluetooth/mgmt.c

@@ -4061,6 +4061,8 @@ static int get_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
 
 	hci_dev_lock(hdev);
 
+	memset(&rp, 0, sizeof(rp));
+
 	if (cp->addr.type == BDADDR_BREDR) {
 		br_params = hci_bdaddr_list_lookup_with_flags(&hdev->whitelist,
 							      &cp->addr.bdaddr,