Chris Pepper
4ab433d391
Fix binary protocol with one serial port (#13270)
- The `sdcard.transfer_port` variable is Marlin's internal serial port index, not the physical serial port number.
- Added packet number to "ok" response so hosts don't need to wait for the ACK.
- Renamed feature to `BINARY_FILE_TRANSFER`, as the speed up is only consequential to the ability to transfer binaries over serial.
Chris Pepper