rcu: Consistent rcu_is_watching() naming

The old rcu_is_cpu_idle() function is just __rcu_is_watching() with
preemption disabled.  This commit therefore renames rcu_is_cpu_idle()
to rcu_is_watching.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index e16c45b..4e8e14c 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -4224,7 +4224,7 @@
 	printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
 	       !rcu_lockdep_current_cpu_online()
 			? "RCU used illegally from offline CPU!\n"
-			: rcu_is_cpu_idle()
+			: !rcu_is_watching()
 				? "RCU used illegally from idle CPU!\n"
 				: "",
 	       rcu_scheduler_active, debug_locks);
@@ -4247,7 +4247,7 @@
 	 * So complain bitterly if someone does call rcu_read_lock(),
 	 * rcu_read_lock_bh() and so on from extended quiescent states.
 	 */
-	if (rcu_is_cpu_idle())
+	if (!rcu_is_watching())
 		printk("RCU used illegally from extended quiescent state!\n");
 
 	lockdep_print_held_locks(curr);