iommu/vt-d: Get domain ID before clear pasid entry

After tearing down a pasid entry, the domain id is used to
invalidate the translation caches. Retrieve the domain id
from the pasid entry value before clearing the pasid entry.
Otherwise, we will always use domain id 0.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Fixes: 6f7db75e ("iommu/vt-d: Add second level page table interface")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>