staging: comedi: amplc_dio200: absorb dio200_subdev_timer_init()

This function is only called by amplc_dio200_common_attach() and it
can never fail. For aesthetics, absorb it into that function.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>