Tools:
- Fix a case of stderr output not be atomic and getting interleaved

- Relax checks on overlapping types

- Fix handling of matrix types with unbounded dimensions

- Apply fixups under "definitions"

Meta-schemas:
- Ensure matrix properties have 2 levels of items

- Exclude "xlnx,channels" from vendor properties as it can be a node
  name, too

Schemas:
- New PCI properties "aspm-no-l1ss" and "aspm-no-l1". Add constraints
  for T_POWER_ON property.

- Drop constraints on iommu-map to support variable #iommu-cells