trx: fix HR1 codec breakage from format change

As of commit 1160cabefb23, the common layer of osmo-bts accepts both
TS 101 318 and RFC 5993 formats for HR1 codec, and always passes
the more basic TS 101 318 format to the BTS model.  Unfortunately,
osmo-bts-trx has model-specific code checking the payload length
that was overlooked in that patch, causing breakage.  Fix that bug.
(The actual channel encoding function in libosmocoding already
accepts 14-byte payloads.)

Related: OS#5688
Fixes: I702e26c3ad5b9d8347e73c6cd23efa38a3a3407e
Change-Id: I0e251faeffb76d2604a4100c848141d239d1d86f
---
M src/osmo-bts-trx/sched_lchan_tchf.c
1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/osmo-bts-trx/sched_lchan_tchf.c b/src/osmo-bts-trx/sched_lchan_tchf.c
index 43a3784..0d0f52a 100644
--- a/src/osmo-bts-trx/sched_lchan_tchf.c
+++ b/src/osmo-bts-trx/sched_lchan_tchf.c
@@ -390,7 +390,7 @@
 		switch (tch_mode) {
 		case GSM48_CMODE_SPEECH_V1: /* FR / HR */
 			if (br->chan != TRXC_TCHF) /* HR */
-				len = GSM_HR_BYTES_RTP_RFC5993;
+				len = GSM_HR_BYTES;
 			else
 				len = GSM_FR_BYTES;
 			break;

