aud-caramel: create handheld.{cfg,vol} equal to hds4.{cfg,vol} The main audio channel on FC Caramel2 is not truly handheld, thus if someone is operating a C2 board in ACI mode, then doing AT@AUL="hds4" is more truthful than AT@AUL="handheld". However, the same audio mode needs to be named "handheld" for the UI firmware to pick it up in our Luna configuration.