gsm_04_08: add more enum gsm48_chan_mode speech values

From 3GPP TS 44.018 (version 15.4.0), table 10.5.2.6.1.

Change-Id: I6adda28698c0e479ef20f5d090c1f7f76a2ec97e
Related: OS#1572
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index 1657864..59393d1 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -448,10 +448,15 @@
 	{ GSM48_CMODE_SPEECH_V1,	"SPEECH_V1" },
 	{ GSM48_CMODE_SPEECH_EFR,	"SPEECH_EFR" },
 	{ GSM48_CMODE_SPEECH_AMR,	"SPEECH_AMR" },
+	{ GSM48_CMODE_SPEECH_V4,	"SPEECH_V4" },
+	{ GSM48_CMODE_SPEECH_V5,	"SPEECH_V5" },
+	{ GSM48_CMODE_SPEECH_V6,	"SPEECH_V6" },
+
 	{ GSM48_CMODE_DATA_14k5,	"DATA_14k5" },
 	{ GSM48_CMODE_DATA_12k0,	"DATA_12k0" },
 	{ GSM48_CMODE_DATA_6k0,		"DATA_6k0" },
 	{ GSM48_CMODE_DATA_3k6,		"DATA_3k6" },
+
 	{ GSM48_CMODE_SPEECH_V1_VAMOS,	"SPEECH_V1_VAMOS" },
 	{ GSM48_CMODE_SPEECH_V2_VAMOS,	"SPEECH_V2_VAMOS" },
 	{ GSM48_CMODE_SPEECH_V3_VAMOS,	"SPEECH_V3_VAMOS" },
@@ -493,6 +498,8 @@
 		return GSM48_CMODE_SPEECH_EFR;
 	case GSM48_CMODE_SPEECH_V3_VAMOS:
 		return GSM48_CMODE_SPEECH_AMR;
+	case GSM48_CMODE_SPEECH_V5_VAMOS:
+		return GSM48_CMODE_SPEECH_V5;
 	default:
 		return mode;
 	}