Input: xpad - use proper endpoint type

The xpad wireless endpoint is not a bulk endpoint on my devices, but
rather an interrupt one, so the USB core complains when it is submitted.
I'm guessing that the author really did mean that this should be an
interrupt urb, but as there are a zillion different xpad devices out
there, let's cover out bases and handle both bulk and interrupt
endpoints just as easily.

Signed-off-by: "Pierre-Loup A. Griffais" <pgriffais@valvesoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>