kcov: don't instrument lib/find_bit.c

kcov: don't instrument lib/find_bit.c

This file produces large amounts of flaky coverage not useful for the
KCOV's intended use case (guiding the fuzzing process).

Link: https://lkml.kernel.org/r/20240722223726.194658-1-andrey.konovalov@linux.dev
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Aleksandr Nogikh <nogikh@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>