UefiCpuPkg/MpInitLib: use PcdConfidentialComputingAttr to check SEV status

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

Previous commit introduced a generic confidential computing PCD that can
determine whether AMD SEV-ES is enabled. Update the MpInitLib to drop the
PcdSevEsIsEnabled in favor of PcdConfidentialComputingAttr.

Cc: Michael Roth <michael.roth@amd.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Ray Ni <ray.ni@intel.com>
Suggested-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

UefiCpuPkg/Library/MpInitLib/MpLib.h

@@ -33,6 +33,7 @@
 #include <Library/HobLib.h>
 #include <Library/PcdLib.h>
 #include <Library/MicrocodeLib.h>
+#include <ConfidentialComputingGuestAttr.h>
 
 #include <Register/Amd/Fam17Msr.h>
 #include <Register/Amd/Ghcb.h>
@@ -773,4 +774,16 @@ SevEsPlaceApHlt (
   CPU_MP_DATA  *CpuMpData
   );
 
+/**
+ Check if the specified confidential computing attribute is active.
+
+ @retval TRUE   The specified Attr is active.
+ @retval FALSE  The specified Attr is not active.
+**/
+BOOLEAN
+EFIAPI
+ConfidentialComputingGuestHas (
+  CONFIDENTIAL_COMPUTING_GUEST_ATTR  Attr
+  );
+
 #endif