fix kenwood_set_mode for ts590s and mode CW, RTTY or AM

Current code always tries to set data mode with 'DAx' command after
setting the mode. According to 'PC control command reference' manual
that results in error for the CW, FSK and AM mode.

The provided patch sends 'DAx' only if we have some of the other modes.

kenwood/kenwood.c

@@ -1197,7 +1197,7 @@ int kenwood_set_rit(RIG * rig, vfo_t vfo, shortfreq_t rit)
 
   if (rit == 0)
     return kenwood_transaction(rig, "RC", NULL, 0);
-  
+
   sprintf(buf, "R%c", (rit > 0) ? 'U' : 'D');
 
   retval = kenwood_transaction(rig, "RC", NULL, 0);
@@ -1206,7 +1206,7 @@ int kenwood_set_rit(RIG * rig, vfo_t vfo, shortfreq_t rit)
 
   for (i = 0; i < abs(rint(rit/10)); i++)
     retval = kenwood_transaction(rig, buf, NULL, 0);
-  
+
   return retval;
 }
 
@@ -1375,10 +1375,17 @@ int kenwood_set_mode(RIG *rig, vfo_t vfo, rmode_t mode, pbwidth_t width)
   if (RIG_MODEL_TS590S == rig->caps->rig_model
       || RIG_MODEL_TS590SG == rig->caps->rig_model)
     {
-      /* supports DATA sub modes - see above */
-      sprintf (buf, "DA%c", data_mode);
-      err = kenwood_transaction (rig, buf, NULL, 0);
-      if (err != RIG_OK) return err;
+      if (!(RIG_MODE_CW == mode
+         || RIG_MODE_CWR == mode
+         || RIG_MODE_AM == mode
+         || RIG_MODE_RTTY == mode
+	 || RIG_MODE_RTTYR == mode))
+        {
+	  /* supports DATA sub modes - see above */
+	  sprintf (buf, "DA%c", data_mode);
+	  err = kenwood_transaction (rig, buf, NULL, 0);
+	  if (err != RIG_OK) return err;
+	}
     }
 
   if (rig->caps->rig_model == RIG_MODEL_TS450S