Change Elecraft K4 to use AB3;FT1 instead of AB0;FT1

https://github.com/Hamlib/Hamlib/issues/825

rigs/kenwood/kenwood.c

@@ -1337,7 +1337,7 @@ int kenwood_set_split_vfo(RIG *rig, vfo_t vfo, split_t split, vfo_t txvfo)
     /* set TX VFO */
     if (rig->caps->rig_model == RIG_MODEL_K4) // K4 needs VFOB to be same band as VFOA
     {
-        snprintf(cmdbuf, sizeof(cmdbuf), "AB0;FT%c", vfo_function);
+        snprintf(cmdbuf, sizeof(cmdbuf), "AB3;FT%c", vfo_function);
     }
     else
     {