SecurityPkg: Add PCD for SW SMI Command port

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2416



Adds a PCD to SecurityPkg used to specify the SW SMI Command port. This
value may vary across platforms and is current hardcoded to 0xB2 in
package code.

Cc: Kun Qin <Kun.Qin@microsoft.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Guomin Jiang <guomin.jiang@intel.com>
Reviewed-by: Bret Barkelew <bret.barkelew@microsoft.com>