[firmware] Implement watchdog timer for internal state

[kbhomes]

Mimic the behavior of a real DualShock controller — after some amount of time with no communication from the console, the controller should automatically reset its state in preparation for a new, future connection.

As it is currently, disconnecting the controller would leave the controller in its current state which may be confusing for the console (or any games) which are expecting a new controller connection to start in plain digital mode.

The Curious Inventor documentation says:

Some controllers have a watch-dog timer that reverts back into digital mode if a command is not received within a second or so.