kasan: rename pagealloc tests

kasan: rename pagealloc tests

Rename "pagealloc" KASAN tests:

1. Use "kmalloc_large" for tests that use large kmalloc allocations.

2. Use "page_alloc" for tests that use page_alloc.

Also clean up the comments.

Link: https://lkml.kernel.org/r/f3eef6ddb87176c40958a3e5a0bd2386b52af4c6.1703024586.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Lobakin <alobakin@pm.me>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>