when we have a bad unsigned firmware we check if it is a good signed
firmware. If it is then we should return OK, if not we should return
the original error code, otherwise we end up giving a misleading
reason for not booting a peripheral
this is important to provide an upgrade path for AP_Periph from
unsigned to signed. It means a bootloader with no public keys can
still check the board ID and CRCs of the signed firmware
this supports fetching, updating and removing public keys using the
SECURE_COMMAND mavlink operations. This will allow for vendors to
remotely hand over management of RemoteID security to new vendors