USB: Add drivers/usb/misc/iowarrior.c to the Makefile

This patch adds the new iowarrior module to the Makefile in drivers/usb.
Currently the module isn't build unless another driver from usb/misc is
selected.

Signed-off-by: Nico Erfurth <masta@perlgolf.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>