ARM: dts: imx6: Add GE B1x5v2

This adds device tree files for the General Electric Healthcare
(GEHC) B1x5v2 series. All models make use of Congatec's QMX6
system on module, which is described in its own device tree include,
so that it can also be used by other boards.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>