cpu/hotplug: Fix comment typo

/s/reatdown/teardown/
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/1621585689-177398-1-git-send-email-john.garry@huawei.com

include/linux/cpuhotplug.h

@@ -399,7 +399,7 @@ static inline int cpuhp_state_remove_instance(enum cpuhp_state state,
 
 /**
  * cpuhp_state_remove_instance_nocalls - Remove hotplug instance from state
- *					 without invoking the reatdown callback
+ *					 without invoking the teardown callback
  * @state:	The state from which the instance is removed
  * @node:	The node for this individual state.
  *