Prettify some code comments

Marlin/src/sd/usb_flashdrive/lib/Usb.cpp

Marlin/src/sd/usb_flashdrive/lib/Usb.h

Marlin/src/sd/usb_flashdrive/lib/UsbCore.h

Marlin/src/sd/usb_flashdrive/lib/address.h

Marlin/src/sd/usb_flashdrive/lib/confdescparser.h

Marlin/src/sd/usb_flashdrive/lib/hexdump.h

Marlin/src/sd/usb_flashdrive/lib/macros.h

Marlin/src/sd/usb_flashdrive/lib/masstorage.cpp

Marlin/src/sd/usb_flashdrive/lib/masstorage.h

Marlin/src/sd/usb_flashdrive/lib/max3421e.h

Marlin/src/sd/usb_flashdrive/lib/message.cpp

Marlin/src/sd/usb_flashdrive/lib/message.h

Marlin/src/sd/usb_flashdrive/lib/parsetools.cpp

Marlin/src/sd/usb_flashdrive/lib/parsetools.h

Marlin/src/sd/usb_flashdrive/lib/printhex.h

Marlin/src/sd/usb_flashdrive/lib/settings.h

Marlin/src/sd/usb_flashdrive/lib/usb_ch9.h