staging: comedi: ni_daq_700: remove exported symbols

This driver exports a number of functions with EXPORT_SYMBOL()
but nothing actually uses them. They also are not declared in
any header for use outside this module.

As stated in the comments, this driver was based on the 8255
driver so these exports are most likely the result of cut-and-
paste from the 8255 driver.

Remove all the EXPORT_SYMBOL() lines. If the exported function
is not used in the driver, remove the entire function as well.
If the function is used, make it static.

Also, make the dio700_cs_driver variable static since it's only
referenced in this file.

This quiets the following sparse warnings:

warning: symbol 'subdev_700_interrupt' was not declared. Should it be static?
warning: symbol 'subdev_700_init' was not declared. Should it be static?
warning: symbol 'subdev_700_init_irq' was not declared. Should it be static?
warning: symbol 'subdev_700_cleanup' was not declared. Should it be static?
warning: symbol 'dio700_cs_driver' was not declared. Should it be static?

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>