staging: comedi: auto-config drivers do not need to set hw_dev

The comedi core now sets the 'hw_dev' pointer in the function
comedi_auto_config_helper() before calling the auto attach
function in the driver.

Remove the now unnecessary call to comedi_set_hw_dev() in the
drivers that use the auto-config attach mechanism.

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