Add support for 16550 UART to ACPI SPCR table as it is a supported UART type by HLOS. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ashish Singhal <ashishsingha@nvidia.com> Reviewed-by: Sami Mujawar <sami.mujawar@arm.com> Reviewed-by: Alexei Fedorov <alexei.fedorov@arm.com>