cpuidle: Drop misleading comments about RCU usage

The commit 1098582 ("sched,idle,rcu: Push rcu_idle deeper into the
idle path"), moved the calls rcu_idle_enter|exit() into the cpuidle core.

However, it forgot to remove a couple of comments in enter_s2idle_proper()
about why RCU_NONIDLE earlier was needed. So, let's drop them as they have
become a bit misleading.

Fixes: 1098582 ("sched,idle,rcu: Push rcu_idle deeper into the idle path")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/cpuidle.c

@@ -142,11 +142,6 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv,
 
 	time_start = ns_to_ktime(local_clock());
 
-	/*
-	 * trace_suspend_resume() called by tick_freeze() for the last CPU
-	 * executing it contains RCU usage regarded as invalid in the idle
-	 * context, so tell RCU about that.
-	 */
 	tick_freeze();
 	/*
 	 * The state used here cannot be a "coupled" one, because the "coupled"
@@ -159,11 +154,6 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv,
 	target_state->enter_s2idle(dev, drv, index);
 	if (WARN_ON_ONCE(!irqs_disabled()))
 		local_irq_disable();
-	/*
-	 * timekeeping_resume() that will be called by tick_unfreeze() for the
-	 * first CPU executing it calls functions containing RCU read-side
-	 * critical sections, so tell RCU about that.
-	 */
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
 		rcu_idle_exit();
 	tick_unfreeze();