crypto: caam - add support for aead null encryption

Add support for the following combinations:
-encryption: null
-authentication: md5, sha* (1, 224, 256, 384, 512)

Signed-off-by: Tudor Ambarus <tudor.ambarus@freescale.com>
Signed-off-by: Horia Geanta <horia.geanta@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>