Remove some obsolete definitions for clarity
- MinAplWork isn't used.
- SuperMode isn't used and is less well known than "SWI OS_EnterOS".
- MEMCADR is now only a magic value returned by OS_UpdateMEMC, so it is clearer to include it literally with comment.
Added a comment to explain the baffling combination of the MEMC1 control register's address with it's value.