staging: comedi: ni_stc.h: remove NI_PRIVATE_COMMON macro

This macro is used to create the private data structure that is used by
the ni_atmio, ni_mio_cs, and ni_pcimio drivers. These drivers all include
the ni_mio_common.c source to provide most of the driver functionality.

The only driver specific information needed to convert the macro into a
proper struct definition is the MAX_N_CALDACS define. This define is used
to size a couple array members in the struct. The ni_atmio and ni_mio_cs
drivers both define MAX_N_CALDACS as 32. The ni_pcimio driver defines it
as (16+16+2). The ni_mio_common file only uses this define to sanity check
that the struct members are large enough for the number of channels in
the calibration subdevice.

Move the MAX_N_CALDACS define to ni_stc.h and set it to the largest number
of caldacs (34).

The ni_atmio and ni_mio_cs drivers also add one additional member to the
private data struct before using the NI_PRIVATE_COMMON macro.

For the ni_atmio driver, the struct pnp_dev pointer can be saved in the
comedi_device as the 'hw_dev'. The (*detach) of this driver can then use
to_pnp_dev() to get it back when detaching the pnp device.

In the ni_mio_cs driver, the struct pcmia_device pointer is not used so
it can simply be removed.

The NI_PRIVATE_COMMON macro can then be converted into a proper struct
definition.

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>