Add support for AT45DB321C

It seems like this model is one-of-a-kind... it shares some properties
with the older versions of the AT45DB series as well as with new ones.

Corresponding to flashrom svn r1724.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
3 files changed