meta-bytedance: 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: Iaf7ff1f0ddf279234b6e1f05f6684b4e5af27334
diff --git a/conf/layer.conf b/conf/layer.conf
index 6fa8da7..1f36655 100644
--- a/conf/layer.conf
+++ b/conf/layer.conf
@@ -7,4 +7,4 @@
 
 BBFILE_COLLECTIONS += "bytedance-layer"
 BBFILE_PATTERN_bytedance-layer = "^${LAYERDIR}/"
-LAYERSERIES_COMPAT_bytedance-layer = "dunfell"
+LAYERSERIES_COMPAT_bytedance-layer = "dunfell gatesgarth"