kasan/arm64: improve comments for KASAN_SHADOW_START/END

kasan/arm64: improve comments for KASAN_SHADOW_START/END

Patch series "kasan: assorted clean-ups".

Code clean-ups, nothing worthy of being backported to stable.

This patch (of 11):

Unify and improve the comments for KASAN_SHADOW_START/END definitions from
include/asm/kasan.h and include/asm/memory.h.

Also put both definitions together in include/asm/memory.h.

Also clarify the related BUILD_BUG_ON checks in mm/kasan_init.c.

Link: https://lkml.kernel.org/r/cover.1703188911.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/140108ca0b164648c395a41fbeecb0601b1ae9e1.1703188911.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>