rcu: Return bool type for rcu_try_advance_all_cbs()

Return a bool type instead of 0 in rcu_try_advance_all_cbs().
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/tree_plugin.h

@@ -1626,7 +1626,7 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
 
 	/* Exit early if we advanced recently. */
 	if (jiffies == rdtp->last_advance_all)
-		return 0;
+		return false;
 	rdtp->last_advance_all = jiffies;
 
 	for_each_rcu_flavor(rsp) {