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/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index 59176df..338c00a 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -472,7 +472,7 @@
 
 	/* if channel is in PDCH mode, deactivate PDCH first */
 	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_PDCH
-	    && (lchan->ts->flags & TS_F_PDCH_MODE)) {
+	    && (lchan->ts->flags & TS_F_PDCH_ACTIVE)) {
 		/* store activation type and handover reference */
 		lchan->dyn_pdch.act_type = act_type;
 		lchan->dyn_pdch.ho_ref = ho_ref;
@@ -1203,7 +1203,7 @@
 
 static int rsl_rx_pdch_act_ack(struct msgb *msg)
 {
-	msg->lchan->ts->flags |= TS_F_PDCH_MODE;
+	msg->lchan->ts->flags |= TS_F_PDCH_ACTIVE;
 
 	/* We have activated PDCH, so now the channel is available again. */
 	do_lchan_free(msg->lchan);
@@ -1213,7 +1213,7 @@
 
 static int rsl_rx_pdch_deact_ack(struct msgb *msg)
 {
-	msg->lchan->ts->flags &= ~TS_F_PDCH_MODE;
+	msg->lchan->ts->flags &= ~TS_F_PDCH_ACTIVE;
 
 	rsl_chan_activate_lchan(msg->lchan, msg->lchan->dyn_pdch.act_type,
 				msg->lchan->dyn_pdch.ho_ref);