HID: logitech-dj: protect the paired_dj_devices access in add_djhid_dev with the lock

	struct hid_device *dj_hiddev;

	struct dj_device *dj_dev;

	u8 device_index = workitem->device_index;

	unsigned long flags;

	/* Device index goes from 1 to 6, we need 3 bytes to store the

	 * semicolon, the index, and a null terminator

	 */

	unsigned char tmpstr[3];

	/* We are the only one ever adding a device, no need to lock */

	if (djrcv_dev->paired_dj_devices[device_index]) {

		/* The device is already known. No need to reallocate it. */

		dbg_hid("%s: device is already known\n", __func__);

	dj_dev->device_index = device_index;

	dj_hiddev->driver_data = dj_dev;

	spin_lock_irqsave(&djrcv_dev->lock, flags);

	djrcv_dev->paired_dj_devices[device_index] = dj_dev;

	spin_unlock_irqrestore(&djrcv_dev->lock, flags);

	if (hid_add_device(dj_hiddev)) {

		dev_err(&djrcv_hdev->dev, "%s: failed adding dj_device\n",

	return;

hid_add_device_fail:

	spin_lock_irqsave(&djrcv_dev->lock, flags);

	djrcv_dev->paired_dj_devices[device_index] = NULL;

	spin_unlock_irqrestore(&djrcv_dev->lock, flags);

	kfree(dj_dev);

dj_device_allocate_fail:

	hid_destroy_device(dj_hiddev);