Harness orientation designation fixes

[hivoltag3]

This was causing me mental anguish

// flip CAN0 and CAN2 if we are flipped
  if (car_harness_status == HARNESS_STATUS_NORMAL) {
    can_flip_buses(0, 2);
  }

[robbederks]

Wouldn't it be easier to just flip the two names?
There are also some compile errors due to some mistakes in the changes

[hivoltag3]

Essentially this is flipping the names and renaming the relay pins to be more consistent and descriptive. IMO it is more easily readable and understandable this way.

[robbederks]

Thank you for fixing it. I'll clone this into a local branch such that the internal HIL tests can run to ensure functionality, and then it can be merged.

[dzid26]

Just in case someone goes deep on this. - It took me a while to grasp this line:

// orientation flipped (PANDA_SBU1->HARNESS_SBU1(relay), PANDA_SBU2->HARNESS_SBU2(ign))

I don't know if this was initial intention of this PR, but it actually makes sense because SBU1 connects to SBU2 inside the USB-C cable:

1,2.

The other big thing is that RX is routed to TX inside USB-C cable. 3

Thanks