Recovery path for Octavo cards via micro SD

[oliver-rew]

So I had an idea for a recovery path for octavo cards using the (currently) unused micro SD card slot, since we have no other recovery path for these cards if their eMMC gets corrupted. The plan is to mod-wire IO6 of the MAX7310 on each octavo card to the pin on the octavo that decides whether to boot from eMMC or micro SD.

This pin is normally pulled high to boot from eMMC, so the normal state for IO6 would always have to be floating or high. However, if a card went unresponsive and we want to boot from the SD card, we would drive IO6 lower and power cycle the card.