staging: comedi: pcl812: rename 'haveMPC508' in boardinfo

Rename this CamelCase member in the boardinfo and change it to a bit-
field flag.

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>