Make TRX rf locking more visible

* log administrative state transitions
* log what's caused it
* while at it, mark boolean variable as such

Change-Id: I3e25a19fac4d0b4886d825c9876771b1f66efe58
Related: SYS#3864
diff --git a/src/libbsc/bsc_vty.c b/src/libbsc/bsc_vty.c
index 42c16e8..3a80f06 100644
--- a/src/libbsc/bsc_vty.c
+++ b/src/libbsc/bsc_vty.c
@@ -3575,7 +3575,7 @@
 	int locked = atoi(argv[0]);
 	struct gsm_bts_trx *trx = vty->index;
 
-	gsm_trx_lock_rf(trx, locked);
+	gsm_trx_lock_rf(trx, locked, "vty");
 	return CMD_SUCCESS;
 }