crypto: bcm - Simplify obtain the name for cipher

The crypto_ahash_alg_name(tfm) can obtain the name for cipher in
include/crypto/hash.h, but now the function is not in use, so we
use it to simplify the code, and optimize the code structure.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>