[IPSEC]: Ensure that state inner family is set

Similar to the issue we had with template families which
specified the inner families of policies, we need to set
the inner families of states as the main xfrm user Openswan
leaves it as zero.

af_key is unaffected because the inner family is set by it
and not the KM.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>