This adds platform code for the Libre Computer CC "Le Potato" board based on a
Meson GXL (S905X) SoC with the Meson GXL configuration.

This initial submission supports UART, MMC/SDCard and Ethernet with the
Internal RMII PHY.

The meson-gxl-s905x-libretech-cc.dts is synchronised from the linux 4.13
stable tree as of 4.13.8.

Reviewed-by: Simon Glass
Signed-off-by: Neil Armstrong