Revert "Add derived UsbTransport class with USB reset method"

This reverts commit ceb7cbf5.

Reason for revert: Broke mac builds:
system/core/fastboot/usb_osx.cpp:513:35: error: use of undeclared identifier 'USB_TRANSACTION_TIMEOUT'
USB_TRANSACTION_TIMEOUT, USB_TRANSACTION_TIMEOUT);
^

Change-Id: Ibe2f9ff2d5c63f9d33f4bd6d9ba962604cf8caeb