Add M25P20-old

This older (ST-branded) revision of M25P20 chip does not support RDID and
hence was not detected correctly. This patch adds a workaround similar
to M25P40-old.

Corresponding to flashrom svn r1652.

Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
2 files changed