staging: comedi: adl_pci9118: use comedi_buf_write_samples()

Use comedi_buf_write_samples() to add the samples to the async buffer.
The number of bytes to add is determined automatically based on the
number of samples and the bytes_per_sample().

Change the return type of move_block_from_dma() to void and remove the
unnecessary check of the return value of comedi_buf_write_samples().
The callers don't check the return and it's really not necessary. If
comedi_buf_write_samples() fails to allocate enough space in the async
buffer to add all the samples it sets the COMEDI_CB_OVERFLOW event.
This will cause the async command to (*cancel) when the events are
handled.

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>