OvmfPkg: detect Xen earlier

This is useful for initializing memory map.

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@14943 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/PlatformPei/Xen.c

@@ -119,19 +119,9 @@ XenDetect (
 **/
 EFI_STATUS
 InitializeXen (
-  VOID
+  UINT32 XenLeaf
   )
 {
-  UINT32 XenLeaf;
-
-  XenLeaf = XenDetect ();
-
-  if (XenLeaf == 0) {
-    return EFI_NOT_FOUND;
-  }
-
-  DEBUG ((EFI_D_INFO, "Xen was detected\n"));
-
   XenConnect (XenLeaf);
 
   //