ARM: dts: Add support for two more Kontron evalkit boards 'N6311 S' and 'N6411 S'

The 'N6311 S' and the 'N6411 S' are similar to the Kontron 'N6310 S'
evaluation kit boards. Instead of the N6310 SoM, they feature a N6311
or N6411 SoM.

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