xfs: remove CPU hotplug infrastructure

There are no users of the cpu hotplug hooks in xfs now, so remove it.
This reverts f1653c2e2831e ("xfs: introduce CPU hotplug
infrastructure").

Signed-off-by: Darrick J. Wong <[e-mail]>
Reviewed-by: Dave Chinner <[e-mail]>

fs/xfs/xfs_super.c

···
 	destroy_workqueue(xfs_alloc_wq);
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-static int
-xfs_cpu_dead(
-	unsigned int		cpu)
-{
-	return 0;
-}
-
-static int __init
-xfs_cpu_hotplug_init(void)
-{
-	int	error;
-
-	error = cpuhp_setup_state_nocalls(CPUHP_XFS_DEAD, "xfs:dead", NULL,
-			xfs_cpu_dead);
-	if (error < 0)
-		xfs_alert(NULL,
-"Failed to initialise CPU hotplug, error %d. XFS is non-functional.",
-			error);
-	return error;
-}
-
-static void
-xfs_cpu_hotplug_destroy(void)
-{
-	cpuhp_remove_state_nocalls(CPUHP_XFS_DEAD);
-}
-
-#else /* !CONFIG_HOTPLUG_CPU */
-static inline int xfs_cpu_hotplug_init(void) { return 0; }
-static inline void xfs_cpu_hotplug_destroy(void) {}
-#endif
-
 STATIC int __init
 init_xfs_fs(void)
 {
···
 
 	xfs_dir_startup();
 
-	error = xfs_cpu_hotplug_init();
-	if (error)
-		goto out;
-
 	error = xfs_init_caches();
 	if (error)
-		goto out_destroy_hp;
+		goto out;
 
 	error = xfs_init_workqueues();
 	if (error)
···
 	xfs_destroy_workqueues();
  out_destroy_caches:
 	xfs_destroy_caches();
- out_destroy_hp:
-	xfs_cpu_hotplug_destroy();
  out:
 	return error;
 }
···
 	xfs_destroy_workqueues();
 	xfs_destroy_caches();
 	xfs_uuid_table_free();
-	xfs_cpu_hotplug_destroy();
 }
 
 module_init(init_xfs_fs);

include/linux/cpuhotplug.h

···
 	CPUHP_FS_BUFF_DEAD,
 	CPUHP_PRINTK_DEAD,
 	CPUHP_MM_MEMCQ_DEAD,
-	CPUHP_XFS_DEAD,
 	CPUHP_PERCPU_CNT_DEAD,
 	CPUHP_RADIX_DEAD,
 	CPUHP_PAGE_ALLOC,