Input: xpad - add constants for GIP interface numbers

Wired GIP devices present multiple interfaces with the same USB identification
other than the interface number. This adds constants for differentiating two of
them and uses them where appropriate

Signed-off-by: Vicki Pfau <vi@endrift.com>
Link: https://lore.kernel.org/r/20230411031650.960322-2-vi@endrift.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>