dt-bindings: arm: fsl: add TQ Systems boards based on i.MX6UL(L)

dt-bindings: arm: fsl: add TQ Systems boards based on i.MX6UL(L)

TQMa6ULx is a SOM family using NXP i.MX6UL CPU family.
TQMa6ULLx is a SOM family using NXP i.MX6ULL CPU family.
Both are available as a socket type as well as an LGA type.
For both variants there are the mainboards MBa6ULx and MBa6ULxL, trailing
'L' is LGA version.
Finally there is the possibility to use the socket module with an LGA
adapter on the MBa6ULxL.

The SOM needs a mainboard, therefore we provide compatibles using this
naming schema:

"tq,imx6ul-<SOM>" for the module and
"tq,imx6ul-<SOM>-<SBC>" for when mounted on the mainboard.
The i.MX6ULL version is done similar.

Signed-off-by: Matthias Schiffer <matthias.schiffer@tq-group.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>