Revert "Add derived UsbTransport class with USB reset method"

This reverts commit ceb7cbf5fde0ff26a35d442135d01e52b0ef0771.

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
diff --git a/fastboot/usb.h b/fastboot/usb.h
index 96eb934..5b44468 100644
--- a/fastboot/usb.h
+++ b/fastboot/usb.h
@@ -52,13 +52,6 @@
     char device_path[256];
 };
 
-class UsbTransport : public Transport {
-    // Resets the underlying transport.  Returns 0 on success.
-    // This effectively simulates unplugging and replugging
-    virtual int Reset() = 0;
-};
-
 typedef int (*ifc_match_func)(usb_ifc_info *ifc);
 
-// 0 is non blocking
-UsbTransport* usb_open(ifc_match_func callback, uint32_t timeout_ms = 0);
+Transport* usb_open(ifc_match_func callback);