Fixed a lot of warnings in USBHost

cores/arduino/USB/CDC.cpp

cores/arduino/USB/samd21_host.c

libraries/USBHost/src/MouseController.cpp

libraries/USBHost/src/Usb.cpp

libraries/USBHost/src/Usb.h

libraries/USBHost/src/UsbCore.h

libraries/USBHost/src/adk.cpp

libraries/USBHost/src/confdescparser.h

libraries/USBHost/src/hidboot.cpp

libraries/USBHost/src/hidboot.h

libraries/USBHost/src/hidescriptorparser.cpp

libraries/USBHost/src/hiduniversal.h

libraries/USBHost/src/message.h

libraries/USBHost/src/printhex.h

libraries/USBHost/src/sink_parser.h

libraries/USBHost/src/usbhub.cpp