vty: Fix BSC_NODE prompt string

Change '%s(bsc)#' to '%s(config-bsc)# '. The missing trailing blank
breaks osmopy's VTYInteract.command() because the blank is contained
in the end patterns which are checked to decide whether to leave the
select loop. Thus trying to execute the 'bsc' command there blocks
the test script forever.

openbsc/src/osmo-bsc/osmo_bsc_vty.c

@@ -43,7 +43,7 @@ static struct osmo_msc_data *osmo_msc_data(struct vty *vty)
 
 static struct cmd_node bsc_node = {
 	BSC_NODE,
-	"%s(bsc)#",
+	"%s(config-bsc)# ",
 	1,
 };