Enables the zephyr usb device stack and mass storage class on the
mimxrt1050_evk board. The mass storage class is backed by the sdhc disk
access driver, so it's now possible to browse and modify the contents of
the SD card from a USB host (your PC). This is in preparation to support
writing a main.py script to the SD card, and then executing it after the
next reset.
78c7e4a859