staging: comedi: adv_pci1723: remove board reset during (*detach)

The pci1723_reset() function simply resets all the analog output channels
to 0V and a +/-10V range. This really isn't necessary when detaching the
driver.

Remove the board reset and just use comedi_pci_detach() directly for the
(*detach).

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>