C6X: replace tick_nohz_stop/restart_sched_tick calls

The following commits replaced the tick_nohz_{stop,restart}_sched_tick
API with separate tick and rcu calls:

  280f0677
  2bbb6817
  1268fbc7

This patch replaces the C6X use of the old API with the newer interfaces.
Signed-off-by: NMark Salter <msalter@redhat.com>

arch/c6x/kernel/process.c

@@ -71,7 +71,8 @@ void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_stop_sched_tick(1);
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (1) {
 			local_irq_disable();
 			if (need_resched()) {
@@ -80,7 +81,8 @@ void cpu_idle(void)
 			}
 			c6x_idle(); /* enables local irqs */
 		}
-		tick_nohz_restart_sched_tick();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 
 		preempt_enable_no_resched();
 		schedule();