Polish for fs/device_test.
Add return params in DebugPrint output.
Drop unused type.
Test polish.
mtp: close session on closing device. use log for debug output.
Refactoring to allow classic MTP code to be enabled again.
usb: set type for error code constants.
mtp: add Device.Configure, a more robust version of OpenSession.
Reinstate the non-Android version, to accomodate Samsung devices.