[IPSEC]: Lock state when copying non-atomic fields to user-space

This patch adds locking so that when we're copying non-atomic fields such as
life-time or coaddr to user-space we don't get a partial result.

For af_key I've changed every instance of pfkey_xfrm_state2msg apart from
expiration notification to include the keys and life-times.  This is in-line
with XFRM behaviour.

The actual cases affected are:

* pfkey_getspi: No change as we don't have any keys to copy.
* key_notify_sa:
	+ ADD/UPD: This wouldn't work otherwise.
	+ DEL: It can't hurt.

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