arm64: dts: freescale: add fsl-lx2160a-mblx2160a board

Add the different serdes configurations as overlays.

Signed-off-by: Gregor Herburger <gregor.herburger@ew.tq-group.com>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>