mtd: cfi_cmdset_0002: Add support for locking OTP memory

This patch adds support for the locking of the one time
programmable (OTP) memory of Micron M29EW devices.

Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>