Input: xpad - add PDP device id 0x02a4

Adds support for a PDP Xbox One controller with device ID
(0x06ef:0x02a4). The Product string for this device is "PDP Wired
Controller for Xbox One - Stealth Series | Phantom Black".

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