Staging: comedi: usbdux: don't initialize semaphores on init

This patch removes usbdux semaphores initialization
from init function as they are initialized later on in
probe function. Also remove init_usb_devices() as it is
not needed anymore.

Signed-off-by: Mariusz Kozlowski <m.kozlowski@tuxland.pl>
Cc: Bernd Porr <BerndPorr@f2s.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Cc: David Schleef <ds@schleef.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>