Input: xpad - note that usb/devices is now at /sys/kernel/debug/

The /proc/bus/usb/devices got moved to sysfs. It is now sitting at:

        /sys/kernel/debug/usb/devices

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>