Update of the src/include/spd.h file with the following improvements:
* Added information on the relevant datasheet(s) and where to get them.
* Added missing #defines for some other config bytes.
* Documented all config bytes a bit better.
* Renamed some #defines to hopefully make their names clearer.
Signed-off-by: Uwe Hermann <firstname.lastname@example.org>
Acked-by: Stefan Reinauer <email@example.com>