hardknott: yocto release

Latest upstream yocto has moved on to the 3.3 hardknott release

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: Ieae36798d66d21c2c642931f06407d3bb2acf163
diff --git a/meta-openpower/conf/layer.conf b/meta-openpower/conf/layer.conf
index 57e0925..6e7d573 100644
--- a/meta-openpower/conf/layer.conf
+++ b/meta-openpower/conf/layer.conf
@@ -9,4 +9,4 @@
 BBFILE_PATTERN_openpower-layer := "^${LAYERDIR}/"
 LAYERVERSION_openpower-layer = "1"
 LAYERDEPENDS_openpower-layer = "core phosphor-layer aspeed-layer"
-LAYERSERIES_COMPAT_openpower-layer = "dunfell gatesgarth"
+LAYERSERIES_COMPAT_openpower-layer = "gatesgarth hardknott"