MdePkg: Add ARM Serial Port Subtype definitions

MdePkg: Add ARM Serial Port Subtype definitions

The Serial Port Console Redirection Table specification Version 1.03 -
August 10, 2015 adds support for Serial Port Subtypes for ARM. These
Subtypes are described in the Table 3 of the Microsoft Debug Port Table
2 (DBG2) Specification - December 10, 2015.

This patch adds macro definitions for these.

Code at: https://github.com/EvanLloyd/tianocore/commit/79678a0f399e97883cfba09275e750861e24cd70

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>