Merge changes from topic "rpix-multi-console" into integration

* changes:
  rpi: docs: Update maintainers file to new RPi directory scheme
  rpi: console: Autodetect Mini-UART vs. PL011 configuration
  rpi3: build: Include GPIO driver in all BL stages
  rpi: Allow using PL011 UART for RPi3/RPi4
  rpi3: console: Use same "clock-less" setup scheme as RPi4
  rpi3: gpio: Simplify GPIO setup