This patch adds support in the USBD configuration and CDC-MSC-HID class for
high-speed USB mode. To enable it the board configuration must define
USE_USB_HS, and either not define USE_USB_HS_IN_FS, or be an STM32F723 or
STM32F733 MCU which have a built-in HS PHY. High-speed mode is then
selected dynamically by passing "high_speed=True" to the pyb.usb_mode()
function, otherwise it defaults to full-speed mode.
This patch has been tested on an STM32F733.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
