ARM: dts: imx: Add support for Advantech/GE Bx50v3

Advantech has 3 carrier boards (B450v3, B650v3, B850v3) which use
the Advantech BA-16 module (based on iMX6D). This file has the
devicetree entries that are common to all 3 boards.

Signed-off-by: Akshay Bhat <akshay.bhat@timesys.com>
Signed-off-by: Justin Waters <justin.waters@timesys.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>