OvmfPkg: introduce PublishPeiMemory

MemDetect actully does too many things, the underlying platform might
want to have more control over memory layout.

Extract the functionality of publishing PEI memory to a dedicated
function.

Also fixed wrong comment while I was there.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14944 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/PlatformPei/Platform.h

@@ -57,6 +57,11 @@ AddUntestedMemoryRangeHob (
   EFI_PHYSICAL_ADDRESS        MemoryLimit
   );
 
+EFI_STATUS
+PublishPeiMemory (
+  VOID
+  );
+
 EFI_PHYSICAL_ADDRESS
 MemDetect (
   VOID