dyn PDCH: TS flags: rename one, add three, as enum

Rename TS_F_PDCH_MODE to TS_F_PDCH_ACTIVE, to more accurately reflect the truth
value's meaning.

Add TS_F_PDCH_ACT_PENDING and TS_F_PDCH_DEACT_PENDING for sysmoBTS (and
possibly other BTS implementations) to remember what to do when the PCU replies
with a channel de/activation. Also add TS_F_PDCH_PENDING_MASK to test for both.

Change from #define to an enum.

Note: These flags are also used in the upcoming osmo-bts-sysmo dyn PDCH
commits, so osmo-bts submission depends on this commit.

Change-Id: I391a103ab599648b0c5d4f3ad613a6d7c48834b3
diff --git a/openbsc/src/libbsc/bsc_vty.c b/openbsc/src/libbsc/bsc_vty.c
index b0f2f62..578b005 100644
--- a/openbsc/src/libbsc/bsc_vty.c
+++ b/openbsc/src/libbsc/bsc_vty.c
@@ -919,7 +919,7 @@
 		gsm_pchan_name(ts->pchan), gsm_ts_tsc(ts));
 	if (ts->pchan == GSM_PCHAN_TCH_F_PDCH)
 		vty_out(vty, " (%s mode)",
-			ts->flags & TS_F_PDCH_MODE ? "PDCH" : "TCH/F");
+			ts->flags & TS_F_PDCH_ACTIVE ? "PDCH" : "TCH/F");
 	vty_out(vty, "%s", VTY_NEWLINE);
 	vty_out(vty, "  NM State: ");
 	net_dump_nmstate(vty, &ts->mo.nm_state);