staging: comedi: adl_pci9118: absorb DMA and non-DMA helpers

Currently the pci9118_ai_docmd_dma() or pci9118_ai_docmd_sampl() helper
is called by the (*do_cmd) to do the final setup for the command. Most
of this invloves setting various bits in 'ai_ctrl' and 'int_ctrl' to
setup the acquisition based on the 'ai_do' mode. Most of this is the
same for the DMA and non-DMA setup. The differences are easily handled
by either checking the cmd trigger sources or if DMA is used.

Absorb the helper functions into the (*do_cmd) to clarify the code.

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>