gsm48_ie: fix gsm48_encode_bearer_cap(): encode bcap->data.transp

Currently this function is hard-coding the "Connection element (octet
6c)" (see Table 10.5.101h/3GPP TS 24.008) to "Transparent" (0).  This
breaks non-transparent data calls.

Use the value from bcap->data.transp.  The decoding equivalent of
this function needs no changes, it does populate this field already.

Change-Id: I7339908864e8a2aef6f2b48a108650167e413c7f
Related: OS#6110, OS#4394
diff --git a/src/gsm/gsm48_ie.c b/src/gsm/gsm48_ie.c
index e431e4f..0cdcb7c 100644
--- a/src/gsm/gsm48_ie.c
+++ b/src/gsm/gsm48_ie.c
@@ -351,7 +351,9 @@
 		lv[i++] = (bcap->data.parity & 7) |
 			  ((bcap->data.interm_rate & 3) << 5);
 		/* octet 6c */
-		lv[i] = 0x80 | (bcap->data.modem_type & 0x1f);
+		lv[i] = 0x80 |
+			((bcap->data.transp & 3) << 5) |
+			(bcap->data.modem_type & 0x1f);
 		break;
 	default:
 		return -EINVAL;