Do nothing when choosing file transfer when in accessory mode

- Before this CL, the device will be disconnected and reconnected
  to accessory mode when choosing "File transfer/Android Auto" in
  accessory mode. Because the USB menu didn't check state of
  function, it should do nothing when choosing
  "File transfer/Android Auto" in accessory mode.

  This CL add condition to check state of function, it will do
  nothing when choosing "File transfer/Android Auto" in
  accessory mode.

Bug: 162451162
Test: make -j42 RunSettingsRoboTests
Change-Id: I1749c6c43d2a192e4ce1bf1ae5343ff8deafbe48