ARM: dts: imx6: Add support for phyBOARD-Mira i.MX 6Quad/Dual RDK

Add support for the PHYTEC phyBOARD-Mira Rapid Development Kit with
i.MX 6Quad/Dual with eMMC or NAND.

Following interfaces are supported:
- Gigabit Ethernet
- USB Host
- CAN
- RS232
- PCIe
- LVDS
- HDMI

Signed-off-by: Christian Hemp <c.hemp@phytec.de>
Signed-off-by: Stefan Christ <s.christ@phytec.de>
Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>