staging: comedi: cb_pcidas: tidy up caldac_8800_write()

Rename this function so it has namespace associated with the driver.

For aesthetics, remove the 'static const' local variables. They don't
add any significant value.

Remove the 'bitstream' local variable. Change the type of the 'value'
param to match the callers type and write_calibration_bitstream()'s
type.

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>