OvmfPkg: sync FADT with QEMU: PM Timer is 24-bit

Clear TMR_VAL_EXT.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13616 6f19259b-4bc3-4df7-8a09-765794883524
1 file changed