Platform/RaspberryPi: Enable Bluetooth and UART in Windows OS

This change is based on edk2-platforms-raspberrypi-pl011-bth-noflow.diff
in https://github.com/worproject/RPi-Bluetooth-Testing/ with the
modifications and additional changes below for enabling Bluetooth
and serial port (Mini UART) in Windows IOT.
  - Remove RPIQ connection for BT_ON/OFF in Uart.asl because it is
    useless. The firmware already turns on the Bluetooth by default.
  - Move the GPIO pin muxing stuff from Uart.asl to ConfigDxe driver.

Testing Done:
  - Successfully booted Windows Windows 10 IOT (20279.1) on SD (made by
    WOR) with the RPi-Windows-Drivers release ver 0.5 downloaded from
    https://github.com/worproject/RPi-Windows-Drivers/releases


    and checked that both Bluetooth and serial port (Mini UART) can
    work fine.
  - Successfully booted VMware ESXi-Arm Fling v1.3 with only serial
    console connection (PL011 UART).

Signed-off-by: Sunny Wang <sunny.wang@arm.com>
Reviewed-by: Pete Batard <pete@akeo.ie>
Tested-by: Pete Batard <pete@akeo.ie>