crypto: ixp4xx - Use crypto_aead_maxauthsize
crypto: ixp4xx - Use crypto_aead_maxauthsize

This patch uses the helper crypto_aead_maxauthsize instead of
directly dereferencing aead_alg.

Signed-off-by: Herbert Xu <ef65de1c7be0aa837fe7b25ba9a7739905af6a55@gondor.apana.org.au>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs