Merge tag 'devicetree-fixes-for-5.8-2' into dt/next

Devicetree fixes for v5.8, take 2:

- Sync dtc to upstream to pick up fixes for I2C bus checks and quiet
  warnings

- Various fixes for DT binding check warnings

- A couple of build fixes/improvements for binding checks

- ReST formatting improvements for writing-schema.rst

- Document reference fixes