Extend gsm_04_08.h with CSFB related definitiosn form 44.018 Rel 15

These are some IEI definitions that we'll need for CSFB Fast Return

Change-Id: I0e101af316438b56d63d43fc2cb16d7caf563d07
diff --git a/include/osmocom/gsm/protocol/gsm_04_08.h b/include/osmocom/gsm/protocol/gsm_04_08.h
index fbd4fe6..c052e4c 100644
--- a/include/osmocom/gsm/protocol/gsm_04_08.h
+++ b/include/osmocom/gsm/protocol/gsm_04_08.h
@@ -1770,8 +1770,10 @@
 #define GSM48_IE_GROUP_CHDES	0x74
 #define GSM48_IE_BA_LIST_PREF	0x75
 #define GSM48_IE_MOB_OVSERV_DIF	0x77
+#define GSM48_IE_CELL_SEL_IND_AFTER_REL	0x77 /* 44.018 Section 9.1.7 */
 #define GSM48_IE_REALTIME_DIFF	0x7b
 #define GSM48_IE_START_TIME	0x7c
+#define GSM48_IE_INDIVIDUAL_PRIORITIES 0x7c /* 44.018 Section 9.1.7 */
 #define GSM48_IE_TIMING_ADVANCE	0x7d
 #define GSM48_IE_GROUP_CIP_SEQ	0x80
 #define GSM48_IE_CIP_MODE_SET	0x90