arm64: dts: freescale: add i.MX8DXL SoC support

i.MX8DXL is a device targeting the automotive and industrial market
segments. The chip is designed to achieve both high performance and
low power consumption. It has a dual (2x) Cortex-A35 processor.

This patch adds the basic support for i.MX8DXL SoC.

Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>