Integrate meta-seco-edgehog-things/davc/change_folder

Commit: edgehog/layers/seco/meta-seco-edgehog-things@193763d8

[BBLAYERS] Place all SECO layers inside meta-seco root folder

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.

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Commit: edgehog/layers/seco/meta-seco-edgehog-things@416054b4

[YCONFIG][RPI] Sign RPI machines compatible with Things DISTROs

Changed Yconfig_distro in order to make compatible this distro with RPI machines.