Merge https://source.denx.de/u-boot/custodians/u-boot-watchdog

- Update MAINTAINERS file (Stefan)
- wdt-uclass.c: add a property u-boot, noautostart (Philippe)
- armada_37xx: Probe driver also when watchdog is already running (Pali)
- rti_wdt: Add 10% safety margin to clock frequency (Jan)