macsec: validate ICV length on link creation

Test the cipher suite initialization in case ICV length has a value
different than its default. If this test fails, creation of a new macsec
link will also fail. This avoids situations where further security
associations can't be added due to failures of crypto_aead_setauthsize(),
caused by unsupported user-provided values of the ICV length.

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>