lib/stackdepot: lower the indentation in stack_depot_init

stack_depot_init does most things inside an if check. Move them out and
use a goto statement instead.

No functional changes.

Link: https://lkml.kernel.org/r/8e382f1f0c352e4b2ad47326fec7782af961fe8e.1676063693.git.andreyknvl@google.com


Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>