gsm_utils: Fix typo in gsm band name

thanks to horizon for noticing :p

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/src/gsm_utils.c b/src/gsm_utils.c
index 913946e..dc97cef 100644
--- a/src/gsm_utils.c
+++ b/src/gsm_utils.c
@@ -199,7 +199,7 @@
 	case GSM_BAND_450:
 		return "GSM450";
 	case GSM_BAND_480:
-		return "GSM450";
+		return "GSM480";
 	case GSM_BAND_750:
 		return "GSM750";
 	case GSM_BAND_810: