crypto: chelsio - check set_msg_len overflow in generate_b0

set_msg_len may fails with -EOVERFLOW, It should be propagate
to upstream.

Fixes: 2debd332

 ("crypto: chcr - Add AEAD algos.")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>