crypto: acomp - Add missing return statements in compress/decompress

The return statements were missing which causes REQ_CHAIN algorithms
to execute twice for every request.

Reported-by: Eric Biggers <ebiggers@kernel.org>
Fixes: 64929fe8 ("crypto: acomp - Remove request chaining")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>