Fix for df8oe#1174 and df8oe#1603: CAT PTT via RTS not returning to RX

This fix will make Virtual RTS return to RX after RTS has been
cleared by the CAT program on PC side.
So  it was not a fault of TR4W in the end but a mistake on our side.
Wonder why it worked in UCXlog.
Please note: This has not been tested yet but should work. In any case it
cannot make it worse...

mchf-eclipse/drivers/cat/cat_driver.c

@@ -53,8 +53,8 @@ static void CatDriver_CatEnableTX(bool enable)
     }
     else
     {
-        ts.ptt_req = false;
         cat_driver.cat_ptt_active = false;
+        ts.tx_stop_req = true;
     }
 }