Svalboard MCU Replacement/Upgrade

Replacement Svalboard MCU (v2B, PFET version) for users interested in upgrading to newer versions for peripheral compatibility or PFET analog bus isolation (somewhat helpful in bright IR environments).  Requires a case upgrade or destructive case modification if coming from from MCU 0.9.

Also requires #define PFET_ROWS in the FW build -- prebuilt FW images available at https://github.com/morganvenable/svalboard-configs

One per order -- order two to upgrade both units.