sched,idle,rcu: Push rcu_idle deeper into the idle path

sched,idle,rcu: Push rcu_idle deeper into the idle path

Lots of things take locks, due to a wee bug, rcu_lockdep didn't notice
that the locking tracepoints were using RCU.

Push rcu_idle_{enter,exit}() as deep as possible into the idle paths,
this also resolves a lot of _rcuidle()/RCU_NONIDLE() usage.

Specifically, sched_clock_idle_wakeup_event() will use ktime which
will use seqlocks which will tickle lockdep, and
stop_critical_timings() uses lock.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Steven Rostedt (VMware) <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Tested-by: Marco Elver <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]