Introduce a new OTP subsystem to be able to interact with One Time
Programmable(OTP) memory. For now, add basic read()/program() APIs.
Program() API is default disabled due to its sensitivity.
File drivers/otp.h is inspired by drivers/eeprom.h as the basic
features are similar.
Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>