types: Remove call_rcu_bh() and call_rcu_sched()

Now that call_rcu()'s callback is not invoked until after bh-disable and
preempt-disable regions of code have completed (in addition to explicitly
marked RCU read-side critical sections), call_rcu() can be used in place
of call_rcu_bh() and call_rcu_sched().  This commit therefore removes
these two API members from the callback_head structure's header comment.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>

include/linux/types.h

@@ -212,8 +212,8 @@ struct ustat {
  * weird ABI and we need to ask it explicitly.
  *
  * The alignment is required to guarantee that bit 0 of @next will be
- * clear under normal conditions -- as long as we use call_rcu(),
- * call_rcu_bh(), call_rcu_sched(), or call_srcu() to queue callback.
+ * clear under normal conditions -- as long as we use call_rcu() or
+ * call_srcu() to queue the callback.
  *
  * This guarantee is important for few reasons:
  *  - future call_rcu_lazy() will make use of lower bits in the pointer;