Improve power handling of the CAN port reverse polarity protection

[henrikssn]

Capturing this discussion from #3:

As a side note, the power handling increase going from the AO3400A to AON7400A is probably lost due to the SS54 diode on the power input being limited to 5A. Using another AON7400A could be suitable for reverse polarity protection instead of the diode. BOM cost increase would be fairly small since the extended part cost of the AON7400A is already done by using it once.

[henrikssn]

@robets The main reason for replacing the AO3400A was safety, it failed short for me with a 60W (2.5A) heater on it and MCU temp at ~100C, I'd like more margin than that. If the SS54 diode fails, then it is much less serious.

Still, the SS54 generates ~2.5W of heat at 5A which would be quite a power dissipation problem (likely won't work) so I think it is a good improvement to replace it with a AON7400A mosfet. It is a bit tricky to make it fit though, and we would need some circuitry (maybe a zener or resistor voltage divider?) for limiting gate voltage (please select something from JLCPCB's basic components).

Another option is to simply remove it, while it is nice it might cause more issues than it solves.