nat: Store the config in the connection instead of the lac

This allows that we can print the Nr. next to the lac
and it allows us to change the lac at runtime without
reconnecting the BSC.
diff --git a/openbsc/src/nat/bsc_nat.c b/openbsc/src/nat/bsc_nat.c
index 1f6b578..2ff06d7 100644
--- a/openbsc/src/nat/bsc_nat.c
+++ b/openbsc/src/nat/bsc_nat.c
@@ -377,9 +377,9 @@
 	llist_for_each_entry(conf, &bsc->nat->bsc_configs, entry) {
 		if (strcmp(conf->token, token) == 0) {
 			bsc->authenticated = 1;
-			bsc->lac = conf->lac;
+			bsc->cfg = conf;
 			bsc_del_timer(&bsc->id_timeout);
-			LOGP(DNAT, LOGL_NOTICE, "Authenticated bsc %d\n", bsc->lac);
+			LOGP(DNAT, LOGL_NOTICE, "Authenticated bsc nr: %d lac: %d\n", conf->nr, conf->lac);
 			break;
 		}
 	}