crypto: hisilicon/sec2 - fix for aead invalid authsize

When the digest alg is HMAC-SHAx or another, the authsize may be less
than 4 bytes and mac_len of the BD is set to zero, the hardware considers
it a BD configuration error and reports a ras error, so the sec driver
needs to switch to software calculation in this case, this patch add a
check for it and remove unnecessary check that has been done by crypto.

Fixes: 2f072d75 ("crypto: hisilicon - Add aead support on SEC2")
Signed-off-by: Wenkai Lin <linwenkai6@hisilicon.com>
Signed-off-by: Chenghai Huang <huangchenghai2@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>