crypto: scompress - free partially allocated scratch buffers on failure

When allocating the per-CPU scratch buffers, we allocate the source
and destination buffers separately, but bail immediately if the second
allocation fails, without freeing the first one. Fix that.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>