This command is used to write-protect (lock) a portion of flash memory,
to prevent accidental overwriting of images. In order to make make any modifications
to the flash, a matching fis unlock command must be
issued. This command is optional and will only be provided on hardware
which can support write-protection of the flash space.
Note: Depending on the system, attempting to write to write-protected flash
may generate errors or warnings, or be benignly quiet.
