crypto: qce - allow building only hashes/ciphers

Allow the user to choose whether to build support for all algorithms
(default), hashes-only, or skciphers-only.

The QCE engine does not appear to scale as well as the CPU to handle
multiple crypto requests.  While the ipq40xx chips have 4-core CPUs, the
QCE handles only 2 requests in parallel.

Ipsec throughput seems to improve when disabling either family of
algorithms, sharing the load with the CPU.  Enabling skciphers-only
appears to work best.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>