Integrate meta-seconorth-distro/tanaro-headless

Commit: seco-ne/yocto/layers/meta-seconorth-distro@5ee31332

fngsystem:self-update: Added new devicetree handling

The handling of custom devicetrees and devicetree overlays has changed. Applied the changes made to the fng-install script to the fngsystem- self-update script as well.

(cherry picked from commit af4918cb1aaa015e5f87d286884729c7d776bb8e)

--

Commit: seco-ne/yocto/layers/meta-seconorth-distro@782ecbf2

tanaro: Add overlay to disable GB ethernet mac when phy is not populated

BCS 746-001157

(cherry picked from commit 1c52dfec53df5a86d29c0914712c64febbd67935)