Staging: comedi: 8255: fix up previous static markings.

Ian pointed out that exported symbols should not be marked as static :)

Fixed this up by properly including the 8255.h file, and fixing
the function prototypes there, as the CONFIG variables were not getting
set so users of the header file were seeing the incorrect function
prototypes.

Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>