staging: comedi: amplc_dio200: Remove thisboard, thislayout and devpriv macros

The 'thisboard', 'thislayout' and 'devpriv' macros rely on a local
variable having a specific name and yield pointers derived from that
local variable.  Replace the macros with local variables wherever they
occur.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>