dt-bindings: arm: fsl: Add more Kontron i.MX6UL/ULL compatibles

Add the compatibles for Kontron i.MX6UL N6311 SoM and boards and
the compatibles for Kontron i.MX6ULL N6411 SoM and boards.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>