Took the existing uavcan_stm32 driver and replaced all bxCAN code with
the equivalent for FDCAN following ST Reference Manual RM0433.
Note: There is still a bug somewhere in regards to FDCAN2 (probably
incorrect setup of the message RAM? Not sure.) But (FD)CAN1 is fully
functional (Classic CAN only, no CAN-FD).
Also TODO: Configure CAN filters. Right now there are no filters; all
incoming messages are accepted.
JacobCrabill