crypto: adiantum - stop using alignmask of shash_alg

Now that the shash algorithm type does not support nonzero alignmasks,
shash_alg::base.cra_alignmask is always 0, so OR-ing it into another
value is a no-op.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>