rcu: Simplify rcu_sched_qs() control flow

This commit applies an early-exit approach to rcu_sched_qs(), reducing
the nesting level and saving a line of code.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/tree.c

@@ -244,7 +244,8 @@ void rcu_sched_qs(void)
 {
 	unsigned long flags;
 
-	if (__this_cpu_read(rcu_sched_data.cpu_no_qs.s)) {
+	if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.s))
+		return;
 	trace_rcu_grace_period(TPS("rcu_sched"),
 			       __this_cpu_read(rcu_sched_data.gpnum),
 			       TPS("cpuqs"));
@@ -255,11 +256,9 @@ void rcu_sched_qs(void)
 	if (__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp)) {
 		__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, false);
 		rcu_report_exp_rdp(&rcu_sched_state,
-					   this_cpu_ptr(&rcu_sched_data),
-					   true);
+				   this_cpu_ptr(&rcu_sched_data), true);
 	}
 	local_irq_restore(flags);
-	}
 }
 
 void rcu_bh_qs(void)