Integrate meta-seconorth-machine/kirkstone-rename-machines

Commit: seco-ne/yocto/layers/meta-seconorth-machine@baffaef0

seco-mx8mp: rename machine from imx8mpguf to seco-mx8mp

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Commit: seco-ne/yocto/layers/meta-seconorth-machine@ef5e0f98

seco-mx8mm: rename machine from imx8mguf to seco-mx8mm

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Commit: seco-ne/yocto/layers/meta-seconorth-machine@37408f71

seco-mx6ull: rename machine from imx6ullguf to seco-mx6ull

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Commit: seco-ne/yocto/layers/meta-seconorth-machine@cd7456bc

seco-mx6: rename machine from imx6guf to seco-mx6