rcu: Fix a kernel-doc warnings for "count"

There are some kernel-doc warnings:

	./kernel/rcu/tree.c:2915: warning: Function parameter or member 'count' not described in 'kfree_rcu_cpu'

This commit therefore moves the comment for "count" to the kernel-doc
markup.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/tree.c

@@ -3004,6 +3004,7 @@ struct kfree_rcu_cpu_work {
  * @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES
  * @monitor_todo: Tracks whether a @monitor_work delayed work is pending
  * @initialized: The @lock and @rcu_work fields have been initialized
+ * @count: Number of objects for which GP not started
  *
  * This is a per-CPU structure.  The reason that it is not included in
  * the rcu_data structure is to permit this code to be extracted from
@@ -3019,7 +3020,6 @@ struct kfree_rcu_cpu {
 	struct delayed_work monitor_work;
 	bool monitor_todo;
 	bool initialized;
-	// Number of objects for which GP not started
 	int count;
 };