HID: logitech-hidpp: ignore very-short or empty names

Some devices report an empty or very short name, in this case stick
with the name generated by the logitech-dj code instead of overriding it
with e.g. "Logitech ".

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

drivers/hid/hid-logitech-hidpp.c

@@ -741,6 +741,9 @@ static char *hidpp_unifying_get_name(struct hidpp_device *hidpp_dev)
 	if (2 + len > sizeof(response.rap.params))
 		return NULL;
 
+	if (len < 4) /* logitech devices are usually at least Xddd */
+		return NULL;
+
 	name = kzalloc(len + 1, GFP_KERNEL);
 	if (!name)
 		return NULL;