broadband-modem: normalize also operator code

The operator code (MCCMNC) may also be given encoded in the current
charset (e.g. UCS2).

Based on a patch from Colin Helliwell <colin.helliwell@ln-systems.com>

src/mm-modem-helpers.c

@@ -3123,8 +3123,8 @@ mm_string_to_access_tech (const gchar *string)
 /*************************************************************************/
 
 void
-mm_3gpp_normalize_operator_name (gchar          **operator,
-                                 MMModemCharset   cur_charset)
+mm_3gpp_normalize_operator (gchar          **operator,
+                            MMModemCharset   cur_charset)
 {
     g_assert (operator);