this is a rework of #5320 started by Andreas then abandoned.
same syntax as in stm32f2x driver:
enable OTP for writing
> stm32l4x otp 1 enable
write to OTP
> flash write_bank 1 foo.bin 0
> flash filld 0x1FFF7000 0xDeadBeafBaadF00d 1
read OTP
> mdw 0x1FFF7000 4
disable OTP
> stm32l4x otp 1 disable
Change-Id: Id7d7c163b35d7a3f406dc200d7e2fc293b0675c2
Signed-off-by: Andreas Bolsch <hyphen0break@gmail.com>
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: http://openocd.zylin.com/5537
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>