VTY: add the dyn_ts_allow_tch_f option

This option allows to enable or disable TCH/F allocation on the
TCH/F_TCH/H_PDCH timeslots. Until now, source code modification
was required to enable this feature.

Related: OS#1778

Change-Id: Id18cab25844dc854a66b4e2713e90c3f43afa712
diff --git a/openbsc/src/libbsc/bsc_vty.c b/openbsc/src/libbsc/bsc_vty.c
index b1747aa..66b30cd 100644
--- a/openbsc/src/libbsc/bsc_vty.c
+++ b/openbsc/src/libbsc/bsc_vty.c
@@ -821,6 +821,8 @@
 	vty_out(vty, " timer t3119 %u%s", gsmnet->T3119, VTY_NEWLINE);
 	vty_out(vty, " timer t3122 %u%s", gsmnet->T3122, VTY_NEWLINE);
 	vty_out(vty, " timer t3141 %u%s", gsmnet->T3141, VTY_NEWLINE);
+	vty_out(vty, " dyn_ts_allow_tch_f %d%s",
+		gsmnet->dyn_ts_allow_tch_f ? 1 : 0, VTY_NEWLINE);
 	vty_out(vty, " subscriber-keep-in-ram %d%s",
 		gsmnet->subscr_group->keep_subscr, VTY_NEWLINE);
 	if (gsmnet->tz.override != 0) {