mm/slub: Finish struct page to struct slab conversion

Update comments mentioning pages to mention slabs where appropriate.
Also some goto labels.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Roman Gushchin <guro@fb.com>

include/linux/slub_def.h

@@ -99,7 +99,7 @@ struct kmem_cache {
 #ifdef CONFIG_SLUB_CPU_PARTIAL
 	/* Number of per cpu partial objects to keep around */
 	unsigned int cpu_partial;
-	/* Number of per cpu partial pages to keep around */
+	/* Number of per cpu partial slabs to keep around */
 	unsigned int cpu_partial_slabs;
 #endif
 	struct kmem_cache_order_objects oo;