OvmfPkg/XenPlatformPei: Detect OVMF_INFO from hvmloader

EFI_XEN_OVMF_INFO is only useful to retrieve the E820 table. The
mXenHvmloaderInfo isn't used yet, but will be use in a further patch to
retrieve the E820 table.

Also remove the unused pointer from the XenInfo HOB as that information
is only useful in the XenPlatformPei.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20190813113119.14804-11-anthony.perard@citrix.com>

OvmfPkg/Include/Guid/XenInfo.h

@@ -18,10 +18,6 @@ typedef struct {
   ///
   VOID *HyperPages;
   ///
-  /// Location of the hvm_info page.
-  ///
-  VOID *HvmInfo;
-  ///
   /// Hypervisor major version.
   ///
   UINT16 VersionMajor;