lib/stackdepot: Fix outdated comments

Replace "depot_save_stack" with "stack_depot_save" in code comments because
depot_save_stack() was replaced in commit c0cfc33726 ("lib/stackdepot:
Provide functions which operate on plain storage arrays") and removed in
commit 56d8f079c5 ("lib/stackdepot: Remove obsolete functions")

Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190815113246.18478-1-miles.chen@mediatek.com

lib/stackdepot.c

@@ -87,7 +87,7 @@ static bool init_stack_slab(void **prealloc)
 		stack_slabs[depot_index + 1] = *prealloc;
 		/*
 		 * This smp_store_release pairs with smp_load_acquire() from
-		 * |next_slab_inited| above and in depot_save_stack().
+		 * |next_slab_inited| above and in stack_depot_save().
 		 */
 		smp_store_release(&next_slab_inited, 1);
 	}
@@ -114,7 +114,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
 		depot_offset = 0;
 		/*
 		 * smp_store_release() here pairs with smp_load_acquire() from
-		 * |next_slab_inited| in depot_save_stack() and
+		 * |next_slab_inited| in stack_depot_save() and
 		 * init_stack_slab().
 		 */
 		if (depot_index + 1 < STACK_ALLOC_MAX_SLABS)