Fix Kenwood TS-2000 split operation.

The API calls to set split frequency and split mode were missing, I
have set them to the preexisting Kenwood functions and they seem to
work as expected. I'm not sure why they were not already enabled.

kenwood/ts2000.c

@@ -288,6 +288,8 @@ const struct rig_caps ts2000_caps = {
 .get_mode =  kenwood_get_mode,
 .set_vfo =  kenwood_set_vfo,
 .get_vfo =  kenwood_get_vfo_if,
+.set_split_vfo = kenwood_set_split_vfo,
+.get_split_vfo = kenwood_get_split_vfo_if,
 .set_ctcss_tone =  kenwood_set_ctcss_tone_tn,
 .get_ctcss_tone =  kenwood_get_ctcss_tone,
 .set_ctcss_sql =  kenwood_set_ctcss_sql,