[IA64] fixed switch to idle domain bug

[IA64] fixed switch to idle domain bug

Previously when switching to idle domain, cr.pta is set to dom0's VHPT,
then when switching from VTIdomain to idle domain, cr.pta is set to
dom0's VHPT, and in idle domain, VHPT will be not remapped by TR, so
there may be unexpected vhpt fault in idle domain, which may cause
domain crash. Above only happens in host smp platform not host up
platform. This patch is intended to fix this bug.

Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Anthony Xu <anthony.xu@intel.com>