Check assoclen to solve the extra tests that expect -EINVAL to be
returned when the associated data size is not valid.

Validated assoclen for RFC4543 which expects an assoclen
of 16 or 20, the same as RFC4106.
Based on seqiv, IPsec ESP and RFC4543/RFC4106 the assoclen is sizeof
IP Header (spi, seq_no, extended seq_no) and IV len. This can be 16 or
20 bytes.
Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>