dm: Remove VLA usage from hashes

In the quest to remove all stack VLA usage from the kernel[1], this uses
the new HASH_MAX_DIGESTSIZE from the crypto layer to allocate the upper
bounds on stack usage.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com



Change-Id: I062967169613d4be0b7256c8092df6e43a7e4eef
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Git-Repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-Commit: 6d39a1241ebc3bdd61d654c3058f0955c28c13fd
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>