staging: comedi: mpc624: tidy up subdevice init

For aesthetics, add some whitespace to the subdevice init. Remove the
unnecessary switch() code used to set the maxdata and range_table.

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>