meta-hpe: 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-hpe rev: bd9e1ac37e64df602226aa0d6c5e205d8d19d84c)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I03dbb43228ed250642b976f9aa55b6ab4d40d54f
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-hpe/conf/layer.conf b/meta-hpe/conf/layer.conf
index 3d2fce1..977654c 100644
--- a/meta-hpe/conf/layer.conf
+++ b/meta-hpe/conf/layer.conf
@@ -7,7 +7,7 @@
 
 BBFILE_COLLECTIONS += "hpe-layer"
 BBFILE_PATTERN_hpe-layer := "^${LAYERDIR}/"
-LAYERSERIES_COMPAT_hpe-layer = "zeus warrior dunfell"
+LAYERSERIES_COMPAT_hpe-layer = "dunfell gatesgarth"
 
 # Provide a variable that points the base of the hpe layer.
 HPEBASE = '${@os.path.normpath("${LAYERDIR}/")}'