Input: add KEY_ROTATE_LOCK_TOGGLE

The key has the same use as the SW_ROTATE_LOCK, but is used on devices
where the state is not tracked by the hardware but has to be handled
in software.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>