meta-ibm: layer.conf: add zeus compatibility

OE-core master will be dropping warrior soon; zeus is the next release.

Change-Id: I0a9c363fbcfac71b3e1f3ccd8f810c8337df5b26
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-witherspoon/conf/layer.conf b/meta-witherspoon/conf/layer.conf
index 62b0678..8cac30c 100644
--- a/meta-witherspoon/conf/layer.conf
+++ b/meta-witherspoon/conf/layer.conf
@@ -7,4 +7,4 @@
 
 BBFILE_COLLECTIONS += "witherspoon-layer"
 BBFILE_PATTERN_witherspoon-layer := "^${LAYERDIR}/"
-LAYERSERIES_COMPAT_witherspoon-layer = "thud warrior"
+LAYERSERIES_COMPAT_witherspoon-layer = "warrior zeus"