[vty] Separate BSC and MSC statistics. Make it easy to print them.

Move the statistics command into the MSC part and move the
BSC statistics printing into a subroutine.
diff --git a/openbsc/src/vty_interface_cmds.c b/openbsc/src/vty_interface_cmds.c
index d494584..623aa30 100644
--- a/openbsc/src/vty_interface_cmds.c
+++ b/openbsc/src/vty_interface_cmds.c
@@ -228,6 +228,17 @@
 	return CMD_SUCCESS;
 }
 
+void openbsc_vty_print_statistics(struct vty *vty, struct gsm_network *net)
+{
+	vty_out(vty, "Channel Requests        : %lu total, %lu no channel%s",
+		counter_get(net->stats.chreq.total),
+		counter_get(net->stats.chreq.no_channel), VTY_NEWLINE);
+	vty_out(vty, "Paging                  : %lu attempted, %lu complete, %lu expired%s",
+		counter_get(net->stats.paging.attempted),
+		counter_get(net->stats.paging.completed),
+		counter_get(net->stats.paging.expired), VTY_NEWLINE);
+}
+
 void openbsc_vty_add_cmds()
 {
 	install_element(VIEW_NODE, &enable_logging_cmd);