x86/virt/tdx: Designate reserved areas for all TDMRs

As the last step of constructing TDMRs, populate reserved areas for all
TDMRs.  Cover all memory holes and PAMTs with a TMDR reserved area.

[ dhansen: trim down chagnelog ]

Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20231208170740.53979-12-dave.hansen%40intel.com