CONFIG_STACK_HASH_ORDER was removed via mainline kernel commit
f9987921cb ("lib/stackdepot: replace CONFIG_STACK_HASH_ORDER with
automatic sizing") at around the same time as this was added via
downstream LKL commit facd006081 ("lkl: add KASAN support").
The automatic sizing uses a minimum of 12, which matches the obsolete
setting.
Signed-off-by: David Disseldorp <ddiss@suse.de>