Integrate meta-seconorth-mtk/add_cfg

Commit: seco-ne/yocto/layers/meta-seconorth-mtk@98aea363

recipes-kernel:files: Add cfg file for seco-genio700

This is an "overlay" file for the standard defconfig, which is applied for specific machine during build. It should be appended instead of a defconfig in linux-seco-mtk/arch/arm64/configs/defconfig