Using the code from PR #2683, thank you @ExplodingWaffle
Removes the dead-battery as selectable option because its unclear if
it can be re-enabled. Also there is no use case for it because the same
resistor can be configured with the sink option.
PD3.0 spec requires concurrent control of CC resistors for collision avoidance.
Needed to introduce some "ref counting" (its just a bool) for drop code.
`select(rx.receive(), tx.transmit()` had subtle interrupt enable race conditions.
Combine receiver and transmitter into one new `PdPhy` struct to disallow the
problematic pattern.
Scanning through the USB PD 2.0 specification there is no need to have RX and TX
running concurrently (after all the USB PD communication is half-duplex).
* Improved interrupt handling: Clear flags in ISR, check state change in future
* Disable pull-up/pull-down resistors and voltage monitor on drop
* nightly rustfmt
Skip FRSTX pin for now. Its available twice in the device JSON as
FRSTX1 and FRSTX2 both with the same pins as targets.
I don’t know enough about the FRS (fast role switch) feature to
understand if that is correct and how to handle the pins.
