Integrate meta-seco-mtk/ap/meta-seco-folder
[FOLDERS] move meta-seco-mtk to meta-seco folder
Move meta-seco-mtk to meta-seco/ as done for the other meta-seco-* layers.
Original commit message: All meta-seco-* layers have been placed inside meta-seco folder. In this way is easier to highlight the code base which composes and characterizes the Edgehog OS distro. All other layers from the third part have been leaved in the same layer as others.