[HSL] initial support for the HSL 2.75G Femtocell

The HSL Femtocell seems to be a poor man implementation of the
ip.access Abis/IP protocol, but cutting corners wherever possible.

We try to workaround those corners wherever possible...
diff --git a/openbsc/src/osmo-nitb/bsc_hack.c b/openbsc/src/osmo-nitb/bsc_hack.c
index 8c6d30b..88814b6 100644
--- a/openbsc/src/osmo-nitb/bsc_hack.c
+++ b/openbsc/src/osmo-nitb/bsc_hack.c
@@ -211,6 +211,7 @@
 extern int bts_model_bs11_init(void);
 extern int bts_model_nanobts_init(void);
 extern int bts_model_rbs2k_init(void);
+extern int bts_model_hslfemto_init(void);
 void talloc_ctx_init(void);
 
 extern enum node_type bsc_vty_go_parent(struct vty *vty);
@@ -241,6 +242,7 @@
 	bts_model_bs11_init();
 	bts_model_nanobts_init();
 	bts_model_rbs2k_init();
+	bts_model_hslfemto_init();
 
 	e1inp_init();