crypto: qce - Clean up qce_auth_cfg

Remove various redundant checks in qce_auth_cfg. Also allow qce_auth_cfg
to take auth_size as a parameter which is a required setting for ccm(aes)
algorithms

Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>