Fix pydfu/libusb issue
Fix pydfu/libusb issue

* See https://github.com/walac/pyusb/issues/94

tianzhihen/openmv,openmv/openmv,tianzhihen/openmv,SmartArduino/openmv,iabdalkader/openmv,tianzhihen/openmv,tianzhihen/openmv,SmartArduino/openmv,openmv/openmv,kwagyeman/openmv,iabdalkader/openmv,SmartArduino/openmv,openmv/openmv,kwagyeman/openmv,iabdalkader/openmv,kwagyeman/openmv,iabdalkader/openmv,openmv/openmv,kwagyeman/openmv,SmartArduino/openmv