osmo_gsm48_classmark_a5_name(): fix 'no-cm3' label

Change-Id: Id84021858dfb2f7d6a7cf81ae73bd94cd47f6776
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index 4166c15..5dc30ad 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -1192,7 +1192,7 @@
 	static char buf[128];
 	char cm1[42] = "no-cm1";
 	char cm2[42] = " no-cm2";
-	char cm3[42] = " no-cm2";
+	char cm3[42] = " no-cm3";
 
 	if (cm->classmark1_set)
 		snprintf(cm1, sizeof(cm1), "cm1{a5/1=%s}",