staging: comedi: pcl816: convert private data flags to bit-fields

The 'irq_was_now_closed' member is actually a flag, devpriv->int816_mode
will always be > 0 when it's used to set irq_was_now_closed in the cancel
function.

Convert the flags in the private data to bit-fields to save a bit of
space.

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>