Add the macros for interfacing with the QEMU feature added in QEMU commit 2f295167e0c4 ("q35/mch: implement extended TSEG sizes", 2017-06-08). Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>