Add 'Bearer Control Mode' IE

This IE is known to be sent by a Cisco GGSN, and was added in
ETSI TS 129 060 V7.17.0 (2011-10) /
3GPP TS 29.060 version 7.17.0 Release 7

See https://lists.osmocom.org/pipermail/osmocom-net-gprs/2016-September/000711.html
Subject "sgsnemu failing to create PDP context with Cisco GGSN"
Tue Sep 13 08:00:37 UTC 2016

Tweaked-by: Neels Hofmeyr <nhofmeyr@sysmocom.de>
diff --git a/gtp/gtpie.c b/gtp/gtpie.c
index a45df1c..c8db449 100644
--- a/gtp/gtpie.c
+++ b/gtp/gtpie.c
@@ -243,6 +243,7 @@
 		case GTPIE_RP_SMS:
 		case GTPIE_RP:
 		case GTPIE_MS_NOT_REACH:
+		case GTPIE_BCM:
 			if (j < GTPIE_SIZE) {
 				ie[j] = (union gtpie_member *)p;
 				if (GTPIE_DEBUG)
@@ -457,6 +458,7 @@
 			case GTPIE_RP_SMS:
 			case GTPIE_RP:
 			case GTPIE_MS_NOT_REACH:
+			case GTPIE_BCM:
 				iesize = 2;
 				break;
 			case GTPIE_FL_DI:	/* TV GTPIE types with value length 2 */
@@ -558,6 +560,7 @@
 				case GTPIE_RP_SMS:
 				case GTPIE_RP:
 				case GTPIE_MS_NOT_REACH:
+				case GTPIE_BCM:
 					iesize = 2;
 					break;
 				case GTPIE_PFI:	/* TV GTPIE types with value length 2 */
diff --git a/gtp/gtpie.h b/gtp/gtpie.h
index 340a76c..fb8598e 100644
--- a/gtp/gtpie.h
+++ b/gtp/gtpie.h
@@ -106,6 +106,7 @@
 #define GTPIE_USER_LOC      152	/* User Location Information  */
 #define GTPIE_MS_TZ         153	/* MS Time Zone */
 #define GTPIE_IMEI_SV       154	/* IMEI Software Version */
+#define GTPIE_BCM           184	/* Bearer control mode */
 /* 239-250 Reserved for the GPRS charging protocol (see GTP' in GSM 12.15) */
 #define GTPIE_CHARGING_ADDR 251	/* Charging Gateway Address */
 /* 252-254 Reserved for the GPRS charging protocol (see GTP' in GSM 12.15) */