meta-nuvoton: 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-nuvoton rev: ff8c4031b99942f6c2ff1cbf10d0f72c403d10db)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Id72267e572724cd1c1dadca2cbd11cb09464e192
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-nuvoton/conf/layer.conf b/meta-nuvoton/conf/layer.conf
index 19af7e9..eaf9a52 100644
--- a/meta-nuvoton/conf/layer.conf
+++ b/meta-nuvoton/conf/layer.conf
@@ -7,4 +7,4 @@
 BBFILE_COLLECTIONS += "nuvoton-layer"
 BBFILE_PATTERN_nuvoton-layer = ""
 LAYERVERSION_nuvoton-layer = "1"
-LAYERSERIES_COMPAT_nuvoton-layer = "warrior zeus dunfell"
+LAYERSERIES_COMPAT_nuvoton-layer = "dunfell gatesgarth"