rcu: Remove unused function declaration rcu_eqs_special_set()

Commit a86baa6 ("rcu: Remove special bit at the bottom of the ->dynticks counter")
left behind this, remove it.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>

Author: Yue Haibing

include/linux/rcutree.h

@@ -37,7 +37,6 @@ void synchronize_rcu_expedited(void);
 void kvfree_call_rcu(struct rcu_head *head, void *ptr);
 
 void rcu_barrier(void);
-bool rcu_eqs_special_set(int cpu);
 void rcu_momentary_dyntick_idle(void);
 void kfree_rcu_scheduler_running(void);
 bool rcu_gp_might_be_stalled(void);