mm/slab: add is_kmalloc_cache() helper function

mm/slab: add is_kmalloc_cache() helper function

commit 6edf2576a6cc ("mm/slub: enable debugging memory wasting of
kmalloc") introduces 'SLAB_KMALLOC' bit specifying whether a kmem_cache is
a kmalloc cache for slab/slub (slob doesn't have dedicated kmalloc
caches).

Add a helper inline function for other components like kasan to simplify
code.

Link: https://lkml.kernel.org/r/20230104060605.930910-1-feng.tang@intel.com
Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>