staging: comedi: 8255: add namespace to 'do_config' function

The name 'do_config' is pretty generic, and this function is the
only one in this driver without namespace. Add namespace to it
just to avoid any issues.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>