lchan release: always Deact SACCH

If an lchan is being released and had a SACCH active, there is no reason to
omit the Deact SACCH message ever. All of the callers that passed
do_deact_sacch = false did so for no good reason.

Drop the do_deact_sacch flag everywhere and, when the lchan type matches and
SAPI[0] is still active, simply always send a Deact SACCH message.

The do_deact_sacch flag was carried over from legacy code, by me, mainly
because I never really understood why it was there. I do hope I'm correct now,
asserting that having this flag makes no sense.

Change-Id: Id3301df059582da2377ef82feae554e94fa42035
diff --git a/tests/gsm0408/gsm0408_test.c b/tests/gsm0408/gsm0408_test.c
index 1e6a097..d15e149 100644
--- a/tests/gsm0408/gsm0408_test.c
+++ b/tests/gsm0408/gsm0408_test.c
@@ -986,7 +986,7 @@
 
 const char *bsc_subscr_name(struct bsc_subscr *bsub) { return NULL; }
 
-void lchan_release(struct gsm_lchan *lchan, bool do_deact_sacch, bool do_rr_release,
+void lchan_release(struct gsm_lchan *lchan, bool do_rr_release,
 		   bool err, enum gsm48_rr_cause cause_rr) {}
 
 int rsl_data_request(struct msgb *msg, uint8_t link_id) { return 0; }