[bkdr_loader] support start/stop address

To load the OTP image into the RRAM data array we need a small adjustment in the backdoor loader.

Instead of clearing the full array we need to be able to only clear a segment.

I think we can add:
- start address
- end address

The operations should behave like this:
- start address should always be respected
- Autoincrement will stop at the end address
- clearing will clear from start to end

The values can be reset to a default after a clear or auto increment operation.