Cleanup ST M50 driver.

There are two locking strategies used by this umbrella family, one uniform
and one that matches the sector layout of the chip. Refactor the functions
involved and rename the overly complicated file to just stm50.c and the
functions accordingly.

This fixes unlocking of some of the non-uniform chips and gets rid of the
abuse of page_size.

Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://flashrom.org/flashrom/trunk@1736 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
Add support for ST M50LPW080.

Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://flashrom.org/flashrom/trunk@1737 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
Enable sector erase function for selected ST M50 chips.

Affected chips: M50FLW040A, M50FLW040B, M50FLW080A, M50FLW080B.

Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://flashrom.org/flashrom/trunk@1738 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1