Integrate meta-seconorth-distro/fix_overlays

Commit: seco-ne/yocto/layers/meta-seconorth-distro@bbcbe53e

install:prepare: Changed substraction with replace

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Commit: seco-ne/yocto/layers/meta-seconorth-distro@db449544

install:prepare: Look for overlays with dtbo and dtb ending

Our 5.10 LTS kernel still uses dtb file endings for the overlays. Check for both endings during the overlay probing.