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).

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I7710b87e89bd61e69dc770692df403ebad0aa383
diff --git a/conf/layer.conf b/conf/layer.conf
index 0a5f6f2..502a8fd 100644
--- a/conf/layer.conf
+++ b/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"