crypto: gcm - helper functions for assoclen/authsize check

Added inline helper functions to check authsize and assoclen for
gcm, rfc4106 and rfc4543.
These are used in the generic implementation of gcm, rfc4106 and
rfc4543.

Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>