mm/kasan: add module decription

mm/kasan: add module decription

Modules without a description now cause a warning:

WARNING: modpost: missing MODULE_DESCRIPTION() in mm/kasan/kasan_test.o

[akpm@linux-foundation.org: update description text, per Andrey]
Link: https://lkml.kernel.org/r/20250324173242.1501003-9-arnd@kernel.org
Fixes: 6c6c1fc09de3 ("modpost: require a MODULE_DESCRIPTION()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
Cc: Macro Elver <elver@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nihar Chaithanya <niharchaithanya@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Cc: Stehen Rothwell <sfr@canb.auug.org.au>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>