staging: comedi: 8255: handle memory mapped io

staging: comedi: 8255: handle memory mapped io

The drivers that use this module with memory mapped io all have the
ioremap'ed base address stored in the comedi_device 'mmio' member.

Introduce a default (*io) function that does 8-bit memory mapped io.

Modify subdev_8255_init() so that it takes a flag parameter indicating
if the io is port or memory mapped. Make the function static and rename
it to __subdev_8255_init().

Introduce two exported wrappers for __subdev_8255_init():

  subdev_8255_init() - for drivers that do 8-bit port io
  subdev_8255_mm_init() - for drivers that do 8-bit memory mapped io

Use subdev_8255_mm_init() in the drivers that do 8-bit memory mapped io
and remove the private (*io) functions.

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>