Introduce a helper function to load the analog output FIFO.
This fixes a bug in cb_pcidas_ao_inttrig(). That function was writing
'num_bytes' data values to the FIFO instead of 'num_points'. This results
in twice the number of data values getting written to the FIFO.
Use comedi_buf_read_samples() read the analog output samples from the async
buffer.
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>