CorebootPayloadPkg: Make serial I/O configurable

Allow the serial port configuration to be overriden from the command
line.
Make the debug serial PCDs patchable in module.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-by: Prince Agyeman <prince.agyeman@intel.com>
2 files changed