staging: comedi: ni_daq_700: remove unused private data variable

staging: comedi: ni_daq_700: remove unused private data variable

The 'have_irq' variable is not needed since this driver doesn't
use interrupts. Remove it.

The kfree(s->private) needs to remain to free the memory allocated
in subdev_700_init().

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