HID: logitech-dj: deal with some KVMs adding an extra interface to the usbdev

My Aten cs1764a KVM adds an extra interface to the receiver through which
it forwards mouse events, if a separate mouse is plugged in next to the
receiver dongle. This interface is present even if no extra mouse is
plugged in.

logitech-dj trying to handle this extra interface causes mouse events send
through the extra interface to not be properly handled.

This commit fixes this by treating any extra interfaces as hid-generic
interfaces.

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