gsm: allow use of GSM 03.38 character set (bgo #627935)

It's only really used for phonebook and SMS PDU mode in the specs,
which we don't do yet, so if this is the only charset the device
supports we'll try to use it.

src/mm-generic-gsm.c

@@ -863,6 +863,7 @@ static guint32 best_charsets[] = {
     MM_MODEM_CHARSET_UCS2,
     MM_MODEM_CHARSET_8859_1,
     MM_MODEM_CHARSET_IRA,
+    MM_MODEM_CHARSET_GSM,
     MM_MODEM_CHARSET_UNKNOWN
 };
 
@@ -921,7 +922,7 @@ supported_charsets_done (MMModem *modem,
     }
 
     /* Switch the device's charset; we prefer UTF-8, but UCS2 will do too */
-    mm_modem_set_charset (modem, MM_MODEM_CHARSET_UTF8, enabled_set_charset_done, info);
+    mm_modem_set_charset (modem, best_charsets[0], enabled_set_charset_done, info);
 }
 
 static void