gsm0808.c: Add TLV definition for LAYER3_HEADER_INFORMATION

This is required for osmo-bsc to parse Alcatel S-12 CIPHER MODE COMMAND
in osmo-bsc.
diff --git a/src/gsm/gsm0808.c b/src/gsm/gsm0808.c
index f67ca78..06ee18e 100644
--- a/src/gsm/gsm0808.c
+++ b/src/gsm/gsm0808.c
@@ -318,6 +318,7 @@
 		[GSM0808_IE_CELL_IDENTIFIER]	    = { TLV_TYPE_TLV },
 		[GSM0808_IE_CHOSEN_CHANNEL]	    = { TLV_TYPE_TV },
 		[GSM0808_IE_LAYER_3_INFORMATION]    = { TLV_TYPE_TLV },
+		[GSM0808_IE_LAYER_3_HEADER_INFORMATION] = { TLV_TYPE_TLV },
 		[GSM0808_IE_SPEECH_VERSION]         = { TLV_TYPE_TV },
 		[GSM0808_IE_CHOSEN_ENCR_ALG]        = { TLV_TYPE_TV },
 	},