meta-aspeed: drop thud compatibility

From the manual on LAYERSERIES_COMPAT:

Lists the versions of the OpenEmbedded-Core for which a layer is
compatible. Using the LAYERSERIES_COMPAT variable allows the layer
maintainer to indicate which combinations of the layer and OE-Core can
be expected to work. The variable gives the system a way to detect when
a layer has not been tested with new releases of OE-Core (e.g. the layer
is not maintained).

Noone is testing OE-core thud + meta-aspeed master, so take the safe
route and don't advertise support.  For compatibility with OE-core thud,
use the thud branch of meta-aspeed.

Change-Id: Ie2dc1deaac0fd1b84029aa50f2e22aee9ad1ee00
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/conf/layer.conf b/conf/layer.conf
index b990839..8c0d502 100644
--- a/conf/layer.conf
+++ b/conf/layer.conf
@@ -7,6 +7,6 @@
 BBFILE_COLLECTIONS += "aspeed-layer"
 BBFILE_PATTERN_aspeed-layer := "^${LAYERDIR}/"
 LAYERVERSION_aspeed-layer = "1"
-LAYERSERIES_COMPAT_aspeed-layer = "thud warrior"
+LAYERSERIES_COMPAT_aspeed-layer = "warrior"
 
 ASPEEDBASE = '${@os.path.normpath("${LAYERDIR}/")}'