PrmPkg: Add PlatformGuid

Adds a "platform GUID" field to the PRM ACPI table. This field
is used by a platform to uniquely identify itself such that it
can be targeted by runtime PRM module updates for that platform.

Platforms using PRM are currently required to set a unique value
for gPrmPkgTokenSpaceGuid.PcdPrmPlatformGuid in their platform
DSC.

Cc: Andrew Fish <afish@apple.com>
Cc: Kang Gao <kang.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Benjamin You <benjamin.you@intel.com>
Cc: Liu Yun <yun.y.liu@intel.com>
Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Liming Gao <gaoliming@byosoft.com.cn>
Acked-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Ankit Sinha <ankit.sinha@intel.com>

PrmPkg/PrmLoaderDxe/PrmAcpiTable.h

@@ -56,6 +56,9 @@ typedef struct {
 
 typedef struct {
   EFI_ACPI_DESCRIPTION_HEADER         Header;                     ///< Standard ACPI description header
+  GUID                                PrmPlatformGuid;            ///< A GUID that uniquely identifies this platform.
+                                                                  ///< Used to check for compatibility in PRM module
+                                                                  ///< runtime updates.
   UINT32                              PrmModuleInfoOffset;        ///< Offset in bytes from the beginning of this
                                                                   ///< structure to the PRM Module Info array
   UINT32                              PrmModuleInfoCount;         ///< Number of entries in the PRM Module Info array