In https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1222094, we enable RDP1 for STM32H7.

The protection works, but the code is very STM32H7-specific, may break if other options are enabled (say, PSTATE), and constitute a significant deviation from how flash protection usually works on our STM32 ECs (for example, RO can only be reprogrammed via BOOT0/DFU mode).

We should document this better in the code, and/or in separate documentation.