meta-ingrasys: 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-ingrasys rev: 7dfbc01f6787cf41bf9be2bd0f5b3c46ce710016)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I359e4ce2c8dcbcfbe77bea3c36cc38398a60c6ba
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>