iommu/vt-d: Factor out invalidation descriptor composition

Separate the logic for constructing IOTLB and device TLB invalidation
descriptors from the qi_flush interfaces. New helpers, qi_desc(), are
introduced to encapsulate this common functionality.

Moving descriptor composition code to new helpers enables its reuse in
the upcoming qi_batch interfaces.

No functional changes are intended.

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Link: https://lore.kernel.org/r/20240815065221.50328-2-tina.zhang@intel.com


Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>