Refactor: controller: Remove stonith-watchdog-timeout validator function

...from options array. Instead, call it from the controller after
validating the options array.

We'll soon be moving the options array to libcrmcommon. There, we don't
have access to controld_verify_stonith_watchdog_timeout() or to the
controller's stonith API connection and node name. New comments and the
following task have more details: https://projects.clusterlabs.org/T749.

Ref T746

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>