imx: imx8mm_beacon: Enable USB

With the updated device tree's having USB support, enable in
U-Boot.  This also requires the addition of the imx8m power
domain, since the USB is gated by the power domain controller.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
2 files changed