HID: Enable HID_QUIRK_MULTI_INPUT for Retro Adaptor

Patch for linux-2.6.35-rc4 mainline kernel to enable Paul Qureshi's
Retro Adapter [http://keio.dk/retroadapter.html], an open source USB
device which allows controllers and joysticks from classic computers
and consoles to work on modern PCs, to appear as two separate devices
under Linux.
Signed-off-by: Peter Edwards <samwise@bagshot-row.org>
Acked-by: Paul Qureshi <retro@world3.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>