Make logging category DLMS generic and reusable for other backends

Make sure old configs using "logging level lms <level>" are still accepted.
Initialization order of VTY componenets need to be resorted since newly
introduced command requires logging VTY node to be already setup
beforehand.

Change-Id: Ia195a74a62a8a3dd6267fb1359acaa5628208d8e
diff --git a/Transceiver52M/osmo-trx.cpp b/Transceiver52M/osmo-trx.cpp
index 16047a9..0ad60ef 100644
--- a/Transceiver52M/osmo-trx.cpp
+++ b/Transceiver52M/osmo-trx.cpp
@@ -588,10 +588,10 @@
 	log_enable_multithread();
 	osmo_stats_init(tall_trx_ctx);
 	vty_init(&g_vty_info);
+	logging_vty_add_cmds();
 	ctrl_vty_init(tall_trx_ctx);
 	trx_vty_init(g_trx_ctx);
 
-	logging_vty_add_cmds();
 	osmo_talloc_vty_add_cmds();
 	osmo_stats_vty_add_cmds();