af_key: Fix selector family initialization.

This propagates the xfrm_user fix made in commit
bcf0dda8 ("[XFRM]: xfrm_user: fix
selector family initialization")

Based upon a bug report from, and tested by, Alan Swanson.
Signed-off-by: NKazunori MIYAZAWA <kazunori@miyazawa.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/key/af_key.c

@@ -1251,7 +1251,7 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct sadb_msg *hdr,
 		x->sel.prefixlen_s = addr->sadb_address_prefixlen;
 	}
 
-	if (x->props.mode == XFRM_MODE_TRANSPORT)
+	if (!x->sel.family)
 		x->sel.family = x->props.family;
 
 	if (ext_hdrs[SADB_X_EXT_NAT_T_TYPE-1]) {