bs11_config: initialize bs11 tall ctx, use instead of bsc ctx

Actually initialize tall_bs11cfg_ctx as named const.

Change-Id: I3b42b29cd1a688cb4c9d1d4e44208509d936e4ef
diff --git a/openbsc/src/utils/bs11_config.c b/openbsc/src/utils/bs11_config.c
index 227b9f8..3420991 100644
--- a/openbsc/src/utils/bs11_config.c
+++ b/openbsc/src/utils/bs11_config.c
@@ -890,6 +890,8 @@
 	struct gsm_network *gsmnet;
 	struct e1inp_line *line;
 
+	tall_bs11cfg_ctx = talloc_named_const(NULL, 0, "bs11-config");
+
 	osmo_init_logging(&log_info);
 	handle_options(argc, argv);
 	bts_model_bs11_init();