mm/memory_hotplug: Update comment for hotplug memory callback priorities

Add clarification to comment for memory hotplug callback ordering as the
current comment does not provide clear language on which callback happens
first.

Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20250829222907.1290912-2-dave.jiang@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: davejiang

include/linux/memory.h

@@ -115,8 +115,8 @@ struct notifier_block;
 struct mem_section;
 
 /*
- * Priorities for the hotplug memory callback routines (stored in decreasing
- * order in the callback chain)
+ * Priorities for the hotplug memory callback routines. Invoked from
+ * high to low. Higher priorities correspond to higher numbers.
  */
 #define DEFAULT_CALLBACK_PRI	0
 #define SLAB_CALLBACK_PRI	1