OvmfPkg/ResetVector: add 5-level paging support

Add macros to check for 5-level paging and gigabyte page support.
Enable 5-level paging for the non-confidential-computing case.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-Id: <20240301074402.98625-7-kraxel@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Oliver Steffen <osteffen@redhat.com>
Cc: Michael Roth <michael.roth@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
[lersek@redhat.com: turn the "Cc:" message headers from Gerd's on-list
 posting into "Cc:" tags in the commit message, in order to pacify
 "PatchCheck.py"]

OvmfPkg/ResetVector/ResetVector.inf

@@ -64,3 +64,4 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdQemuHashTableSize
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
+  gEfiMdeModulePkgTokenSpaceGuid.PcdUse5LevelPageTable