imx: i.mx6q: add the initial support for LogicPD i.MX6Q SOM

imx: i.mx6q: add the initial support for LogicPD i.MX6Q SOM

Logic PD has an i.MX6Q system on module (SOM) with a development kit. The
SOM has a built-in microSD socket, DDR and NAND flash.  The development kit
has an SMSC Ethernet PHY, serial debug port and a variety of peripherals.
This have been verified to boot the i.MX6Q version over either SD
on the development kit or NAND built into the SOM.  Items in the dtsi file
are specific to the SOM itself.  Items in the dts file are in the baseboard.
Future versions of the SOM will come out supporting the same basebord and
potentially future base boards will come out supporting the same SOM.

Signed-off-by: Adam Ford <aford173@gmail.com>