Remove undefined param passed to logging_vty_add_cmds

Since March 15th 2017, libosmocore API logging_vty_add_cmds() had its
parameter removed (c65c5b4ea075ef6cef11fff9442ae0b15c1d6af7). However,
definition in C file doesn't contain "(void)", which means number of
parameters is undefined and thus compiler doesn't complain. Let's remove
parameters from all callers before enforcing "(void)" on it.

Change-Id: Ic3c578347864fa225feb6d2dbe14798b9c19ace0
Related: OS#4138

src/osmo-bsc/bsc_vty.c

@@ -5255,7 +5255,7 @@ int bsc_vty_init(struct gsm_network *network)
 	install_element(ENABLE_NODE, &assignment_any_cmd);
 	install_element(ENABLE_NODE, &handover_any_to_arfcn_bsic_cmd);
 
-	logging_vty_add_cmds(NULL);
+	logging_vty_add_cmds();
 	osmo_talloc_vty_add_cmds();
 
 	install_element(GSMNET_NODE, &cfg_net_neci_cmd);