staging: comedi: pcl711: rename some of the register map defines

Rename some of the register map defines so they all have the same
format. Add a couple new defines to tidy up some of the magic
numbers used with the registers.

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>