smpboot: Place the __percpu annotation correctly

The test robot reported a wrong assignment of a per-CPU variable which
it detected by using sparse and sent a report. The assignment itself is
correct. The annotation for sparse was wrong and hence the report.
The first pointer is a "normal" pointer and points to the per-CPU memory
area. That means that the __percpu annotation has to be moved.

Move the __percpu annotation to pointer which points to the per-CPU
area. This change affects only the sparse tool (and is ignored by the
compiler).
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: f97f8f06 ("smpboot: Provide infrastructure for percpu hotplug threads")
Link: http://lkml.kernel.org/r/20190424085253.12178-1-bigeasy@linutronix.deSigned-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/smpboot.h

@@ -29,7 +29,7 @@ struct smpboot_thread_data;
  * @thread_comm:	The base name of the thread
  */
 struct smp_hotplug_thread {
-	struct task_struct __percpu	**store;
+	struct task_struct		* __percpu *store;
 	struct list_head		list;
 	int				(*thread_should_run)(unsigned int cpu);
 	void				(*thread_fn)(unsigned int cpu);