meta-quanta: update Yocto compat for gatesgarth

The next release of Yocto is soon and most of the upstream
layers have switched support strings for it.  Support layer
compat for gatesgarth (current) and dunfell (previous).

(From meta-quanta rev: 34f30a0dca7ab63d93d56132f93e96244b02aeff)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I388aa5bf43235718668da109ebdb800e27b856d0
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>