staging: comedi: ni_daq_dio24: cleanup dio24_detach

Simplify the call to subdev_8255_cleanup() to remove the
need for a local variable.

This driver only attaches to pcmcia devices so the test for
thisboard != pcmcia_bustype will always fail. Remove the test
and the unreachable release_region().

This driver also never does a request_irq() so remove the
free_irq().

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