staging: comedi: comedi_isadma: introduce helper module for ISA DMA

Introduce a new helper module to consolidate all the ISA DMA code. This will
allow removing the "depends on ISA_DMA_API" from the legacy drivers that can
use DMA for async command support.

This module is complete based on the various uses of ISA DMA in the comedi
drivers.

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>

diff --cc drivers/staging/comedi/Kconfig
Simple merge

diff --cc drivers/staging/comedi/drivers/Makefile
Simple merge

diff --cc drivers/staging/comedi/drivers/comedi_isadma.c
Simple merge

diff --cc drivers/staging/comedi/drivers/comedi_isadma.h
Simple merge