mm: use ARRAY_END() instead of open-coding it

mm: use ARRAY_END() instead of open-coding it

There aren't any bugs in this code; it's purely cosmetic.

By using ARRAY_END(), we prevent future issues, in case the code is
modified; it has less moving parts.  Also, it should be more readable (and
perhaps more importantly, greppable), as there are several ways of writing
an expression that gets the end of an array, which are unified by this API
name.

Link: https://lkml.kernel.org/r/2335917d123891fec074ab1b3acfb517cf14b5a7.1765449750.git.alx@kernel.org
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christopher Bazley <chris.bazley.wg14@gmail.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>