ARM: dts: imx6ul: Add DTS for liteBoard

liteBoard is a development board which uses liteSOM as its base.

Hardware specification:
 * liteSOM (i.MX6UL, DRAM, eMMC)
 * Ethernet PHY (id 0)
 * USB host (usb_otg1)
 * MicroSD slot (uSDHC1)

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>