bsc: Create a osmo_bsc_data and embed osmo_msc_data

We want to have multiple MSCs but we also have some data
that is only present on a per BSC basis. Right now the
MSC data is not allocated with talloc, so we have some
change in the talloc contexts.
diff --git a/openbsc/src/osmo-bsc/osmo_bsc_rf.c b/openbsc/src/osmo-bsc/osmo_bsc_rf.c
index 64cab5d..e3f4e99 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_rf.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_rf.c
@@ -160,9 +160,9 @@
 {
 	rf->grace_timeout.cb = grace_timeout;
 	rf->grace_timeout.data = rf;
-	osmo_timer_schedule(&rf->grace_timeout, rf->gsm_network->msc_data->mid_call_timeout, 0);
+	osmo_timer_schedule(&rf->grace_timeout, rf->gsm_network->bsc_data->mid_call_timeout, 0);
 	LOGP(DLINP, LOGL_NOTICE, "Going to switch RF off in %d seconds.\n",
-	     rf->gsm_network->msc_data->mid_call_timeout);
+	     rf->gsm_network->bsc_data->mid_call_timeout);
 
 	send_signal(rf, S_RF_GRACE);
 	return 0;