[PATCH][SERIAL] mpsc updates

Hi again, Andrew. This patch: - replaces several macros with the actual code - change the type of pointer variables from u32 to void * - removes unecessary casts - puts the contents of mpsc_defs.h into mpsc.h and removes the mpsc_defs.h - reflects the new names of some structs - cleans up some

[PATCH][SERIAL] mpsc updates

Hi again, Andrew. This patch: - replaces several macros with the actual code - change the type of pointer variables from u32 to void * - removes unecessary casts - puts the contents of mpsc_defs.h into mpsc.h and removes the mpsc_defs.h - reflects the new names of some structs - cleans up some