braille: Provide base support for automatic, USB and Bluetooth ports using bdDetect. Simplify support for serial ports.
Rather than implementing etPossiblePorts directly, drivers should now provide bdDetect data and implement getManualPorts as appropriate. The base implementation of getPossiblePorts adds the automatic, USB and Bluetooth ports as appropriate.
braille.getSerialPorts can be used in BrailleDisplayDriver.getManualPorts for displays which support serial ports.