rest_octets: Use correct symbols names for range encoder

As gsm48_rest_octets.c is not listed in the Makefile.am, it's
never actually compiled and we never noticed that it's calling
functions by symbol names that don't exist :/

Change-Id: I7b1e436f70e0c60979261db87606f38271ec47d3
Related: OS#3075
diff --git a/src/gsm/gsm48_rest_octets.c b/src/gsm/gsm48_rest_octets.c
index cdb61f1..0171fd9 100644
--- a/src/gsm/gsm48_rest_octets.c
+++ b/src/gsm/gsm48_rest_octets.c
@@ -256,13 +256,13 @@
 	/* Select the range and the amount of bits needed */
 	switch (r) {
 	case OSMO_GSM48_ARFCN_RANGE_128:
-		return osmo_gsm48_range_enc_range128(chan_list, f0, w);
+		return osmo_gsm48_range_enc_128(chan_list, f0, w);
 	case OSMO_GSM48_ARFCN_RANGE_256:
-		return osmo_gsm48_range_enc_range256(chan_list, f0, w);
+		return osmo_gsm48_range_enc_256(chan_list, f0, w);
 	case OSMO_GSM48_ARFCN_RANGE_512:
-		return osmo_gsm48_range_enc_range512(chan_list, f0, w);
+		return osmo_gsm48_range_enc_512(chan_list, f0, w);
 	case OSMO_GSM48_ARFCN_RANGE_1024:
-		return osmo_gsm48_range_enc_range1024(chan_list, f0, f0_included, w);
+		return osmo_gsm48_range_enc_1024(chan_list, f0, f0_included, w);
 	default:
 		return -ERANGE;
 	};