layer.conf: add honister to LAYERSERIES_COMPAT, remove gatesgarth
The override syntax was changed in Yocto master & honister core layers to
repace '_' the deliminator with ':'. New syntax is supported in older releases
if bitbake patches are applied.
Add honister and remove older layers from LAYERSERIS_COMPAT, except dunfell
LTS release.
Signed-off-by: Geoff Parker <geoffrey.parker@arthrex.com>