Common watchdog properties.

Optional properties:
- timeout-sec : Timeout of the watchdog in seconds
                If this timeout is not defined, the value of WATCHDOG_TIMEOUT_MSECS will
                be used instead.
- hw_margin_ms : Period used to reset the watchdog in ms
                 If this period is not defined, the default value is 1000.
- u-boot,noautostart : Specify that this watchdog should not autostart
                       When the config option WATCHDOG_AUTOSTART is set, all enabled
                       watchdogs are started. This property allows specifying that this
                       watchdog should NOT be started.
