Add cmac(aes) keyed hash offloading support.

Similar to xcbc implementation, driver must make sure there are still
some bytes buffered when ahash_final() is called. This way HW is able to
decide whether padding is needed and which key to derive (L -> K1 / K2)
for the last block.
Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>