meta-ibm: layer.conf: Add warrior compatibility

oe-core branched in preparation for the upcoming 2.7 Yocto release and
as of 13e45ff requires core layer compatibility to "warrior" instead of
"thud".  We'll retain compatibility for both until we do our own branch
or stop testing thud.

Change-Id: I1cf1bc580ae5d607f308d11330f13f2503f733f4
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-palmetto/conf/layer.conf b/meta-palmetto/conf/layer.conf
index 61c7538..4bc43ef 100644
--- a/meta-palmetto/conf/layer.conf
+++ b/meta-palmetto/conf/layer.conf
@@ -7,4 +7,4 @@
 
 BBFILE_COLLECTIONS += "palmetto-layer"
 BBFILE_PATTERN_palmetto-layer = ""
-LAYERSERIES_COMPAT_palmetto-layer = "thud"
+LAYERSERIES_COMPAT_palmetto-layer = "thud warrior"