sched_lchan_tchx: use GSM_HR_BYTES_RTP_RFC5993 constant

osmo-bts-trx uses the RFC5993 RTP payload format, so when handling the
RTP payload use GSM_HR_BYTES_RTP_RFC5993, instead of GSM_HR_BYTES + 1

Depends: libosmocore.git I125ef9cdab98c073971841c175b1a7dcd927f9c2
Related: OS#5688
Change-Id: I54dd3adab88e2262913f7b1e89340a0246c88a8a
---
M src/osmo-bts-trx/sched_lchan_tchf.c
M src/osmo-bts-trx/sched_lchan_tchh.c
2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/osmo-bts-trx/sched_lchan_tchf.c b/src/osmo-bts-trx/sched_lchan_tchf.c
index 256125b..da4a475 100644
--- a/src/osmo-bts-trx/sched_lchan_tchf.c
+++ b/src/osmo-bts-trx/sched_lchan_tchf.c
@@ -414,7 +414,7 @@
 		switch (tch_mode) {
 		case GSM48_CMODE_SPEECH_V1: /* FR / HR */
 			if (br->chan != TRXC_TCHF) /* HR */
-				len = GSM_HR_BYTES + 1; /* RFC 5993 */
+				len = GSM_HR_BYTES_RTP_RFC5993;
 			else
 				len = GSM_FR_BYTES;
 			break;
diff --git a/src/osmo-bts-trx/sched_lchan_tchh.c b/src/osmo-bts-trx/sched_lchan_tchh.c
index 37fd59d..41965c4 100644
--- a/src/osmo-bts-trx/sched_lchan_tchh.c
+++ b/src/osmo-bts-trx/sched_lchan_tchh.c
@@ -184,7 +184,7 @@
 		rc = gsm0503_tch_hr_decode(tch_data, *bursts_p,
 					   !sched_tchh_ul_facch_map[bi->fn % 26],
 					   &n_errors, &n_bits_total);
-		if (rc == (GSM_HR_BYTES + 1)) { /* only for valid *speech* frames */
+		if (rc == GSM_HR_BYTES_RTP_RFC5993) { /* only for valid *speech* frames */
 			/* gsm0503_tch_hr_decode() prepends a ToC octet (see RFC5993), skip it */
 			bool is_sid = osmo_hr_check_sid(&tch_data[1], GSM_HR_BYTES);
 			if (is_sid) /* Mark SID frames as such: F = 0, FT = 010 */

