[PATCH] local_lock: Provide INIT_LOCAL_LOCK().

The original code was using INIT_LOCAL_LOCK() and I tried to sneak
around it and forgot that this code also needs to compile on !RT
platforms.

Provide INIT_LOCAL_LOCK() to initialize properly on RT and do nothing on
!RT. Let random.c use which is the only user so far and oes not compile
on !RT otherwise.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>