aspeed: add yocto 2.6 compatibility

Change-Id: I05a4e33c2f5283975717a86467107dca16c6f2eb
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/conf/layer.conf b/conf/layer.conf
index dcd420b..7e316fd 100644
--- a/conf/layer.conf
+++ b/conf/layer.conf
@@ -7,6 +7,6 @@
 BBFILE_COLLECTIONS += "aspeed-layer"
 BBFILE_PATTERN_aspeed-layer = ""
 LAYERVERSION_aspeed-layer = "1"
-LAYERSERIES_COMPAT_aspeed-layer = "sumo"
+LAYERSERIES_COMPAT_aspeed-layer = "thud"
 
 ASPEEDBASE = '${@os.path.normpath("${LAYERDIR}/")}'