intel_iommu: Add missed reserved bit check for IEC descriptor

intel_iommu: Add missed reserved bit check for IEC descriptor

IEC descriptor is 128-bit invalidation descriptor, must be padded with
128-bits of 0s in the upper bytes to create a 256-bit descriptor when
the invalidation queue is configured for 256-bit descriptors (IQA_REG.DW=1).

Fixes: 02a2cbc872df ("x86-iommu: introduce IEC notifiers")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20241104125536.1236118-4-zhenzhong.duan@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>