crypto: kdf - Select hmac in addition to sha256

In addition to sha256 we must also enable hmac for the kdf self-test
to work.

Reported-by: kernel test robot <oliver.sang@intel.com>
Fixes: 304b4ace ("crypto: kdf - select SHA-256 required...")
Fixes: 026a733e

 ("crypto: kdf - add SP800-108 counter key...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>