Platform/RaspberryPi: Dynamically build UARTs info in ACPI

Changes:
  1. Add code to ConfigDxe driver and AcpiTables module to dynamically
     build either Mini UART or PL011 UART info in ACPI. This also fixes
     the issue discussed in https://github.com/pftf/RPi4/issues/118

.
  2. Cleanup by moving duplicate Debug Port 2 table related defines and
     structures to a newly created header file (RpiDebugPort2Table.h).

Testing Done:
  - Booted to UEFI shell and use acpiview command to check the result of
    the different UART settings in config.txt (enabling either Mini UART
    or PL011) and SPCR, DBG2 tables and device BTH0 are dynamically
    changed as expected.

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