meta-yadro: 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 dunsfell (previous).

(From meta-yadro rev: e18f52c26682880d7611a65888a0d8bbc8b5f734)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ia15eb84ee2f655a2d7fcecb96b9edaa95c25539d
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-yadro/conf/layer.conf b/meta-yadro/conf/layer.conf
index 0a5f6f2..502a8fd 100644
--- a/meta-yadro/conf/layer.conf
+++ b/meta-yadro/conf/layer.conf
@@ -9,4 +9,4 @@
 BBFILE_PATTERN_yadro-layer = "^${LAYERDIR}/"
 BBFILE_PATTERN_IGNORE_EMPTY_yadro-layer = "1"
 
-LAYERSERIES_COMPAT_yadro-layer = "warrior zeus dunfell"
+LAYERSERIES_COMPAT_yadro-layer = "dunfell gatesgarth"