Integrate linux-imx-kuk/fix_d18_dts

Commit: seco-ne/kernel/linux-imx-kuk@224c9a76

arm64:dts:seco: Revert deletion of seco-imx8mp-d18.dts

This partly reverts commit 8fa40ae3. In the original commit, the devicetree was split into two. With the splitting, cherry-picks from the upstream repo doesn't work anymore. As a workaround, we revert the seco-imx8mp-d18.dts to its original state, include it in a new devicetree include and remove the B79 nodes there.