lib/test_meminit: destroy cache in kmem_cache_alloc_bulk() test

Make do_kmem_cache_size_bulk() destroy the cache it creates.

Link: https://lkml.kernel.org/r/aced20a94bf04159a139f0846e41d38a1537debb.1640018297.git.andreyknvl@google.com
Fixes: 03a9349a

 ("lib/test_meminit: add a kmem_cache_alloc_bulk() test")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>