ip xfrm state: Allow different selector family

My previous commit introduced a patch to allow for states with different
ip address families for selector and id. The must have somehow been a
mixup of the patch I tested and the one I send, so the patch sent breaks
the iproute2 build. This patch fixes this. My apologies.

Signed-off-by: Thomas Egerer <hakke_007@gmx.de>
diff --git a/ip/xfrm_state.c b/ip/xfrm_state.c
index 6ff5b51..c0cf88c 100644
--- a/ip/xfrm_state.c
+++ b/ip/xfrm_state.c
@@ -296,7 +296,7 @@
 			preferred_family = AF_UNSPEC;
 			xfrm_selector_parse(&req.xsinfo.sel, &argc, &argv);
-			preferred_family = req.xsinfo.sel;
+			preferred_family = req.xsinfo.sel.family;
 		} else if (strcmp(*argv, "limit") == 0) {
 			xfrm_lifetime_cfg_parse(&req.xsinfo.lft, &argc, &argv);