This unique identifier is currently used only for ensuring uniqueness in
sysfs. However, this could be handful for userspace to refer to a specific
hid_device by this id.

2 use cases are in my mind: LEDs (and their naming convention), and
HID-BPF.
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20220902132938.2409206-9-benjamin.tissoires@redhat.com