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>