Staging: comedi: fix 80 character line issue in 8253.h

This is a patch to the 8253.h file to fix 80 character line warning
found by checkpatch.pl tool

Signed-off-by: Graham M Howe <gman.1352@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>