staging: comedi: cb_pcidas: absorb caldac/trimpot write functions

These functions are all just wrappers for cb_pcidas_calib_write().
Remove them and absorb the code into the callers.

Remove the unnecessary masking of the 'chan'. It will always be in
range due to the subdevice initialization.

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>