[MTD] Merge STMicro NOR_ECC code with Intel Sibley code

In 2002, STMicro started producing NOR flashes with internal ECC protection
for small blocks (8 or 16 bytes).  Support for those flashes was added by me.
In 2005, Intel Sibley flashes copied this strategy and Nico added support for
those.  Merge the code for both.

Signed-off-by: Joern Engel <joern@wh.fh-wedel.de>