Try to support watchdog

Here is some background information:

• A customer is following the doc and fails to create an ARM VM with a watchdog
  • Either we need to add this i6300esb Intel PCI device or
  • We need to fix the doc. Other resource from Rich
  • See some references to watchdog in kubevirt doc so most probably we shall try supporting it
  • CONFIG_I6300ESB_WDT seems supported in Linux
• More things to be figured out:
  • Is i6300esb the device we want?
  • Should we evaluate wadt_wdt (https://lwn.net/Articles/701235/) to possibly accommodate Windows guests in the future?
  • Or should we support both?