bsc: change bsc_vty_init to take logging categories as parameter

This change is required to finish the integration of the VTY and
the per-application logging categories that provides:

"vty: integration with logging framework"

in libosmocore.

It has been tested with osmo-nitb. The other just compiled tested.
diff --git a/openbsc/src/osmo-nitb/bsc_hack.c b/openbsc/src/osmo-nitb/bsc_hack.c
index 357ec7a..9ea1879 100644
--- a/openbsc/src/osmo-nitb/bsc_hack.c
+++ b/openbsc/src/osmo-nitb/bsc_hack.c
@@ -251,7 +251,7 @@
 
 	/* This needs to precede handle_options() */
 	vty_init(&vty_info);
-	bsc_vty_init();
+	bsc_vty_init(&log_info);
 
 	/* parse options */
 	handle_options(argc, argv);