The Microsoft Debug Port Table 2 (DBG2) specification revision October 6, 2015 adds support for Serial Port Subtypes for ARM. This patch adds these definitions. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Evan Lloyd <evan.lloyd@arm.com> Reviewed-by: Yao Jiewen <jiewen.yao@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com>