staging: comedi: rti800: tidy up the register map defines

Convert the register defines to hex and the register bit defines
to bit shifts.

Rename the CSR register bit defines to help document them and move
them so they are associated with the register.

Rename the RTI800_SIZE define to RTI800_IOSIZE.

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