meta-nuvoton: prepare for yocto 2.6

Set compatibility to thud.

Change-Id: Ia644cc6683fad47349de818975ddc768cf66ad37
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/conf/layer.conf b/conf/layer.conf
index fe22772..8c5d9d8 100644
--- a/conf/layer.conf
+++ b/conf/layer.conf
@@ -7,4 +7,4 @@
 BBFILE_COLLECTIONS += "nuvoton-layer"
 BBFILE_PATTERN_nuvoton-layer = ""
 LAYERVERSION_nuvoton-layer = "1"
-LAYERSERIES_COMPAT_nuvoton-layer = "sumo"
+LAYERSERIES_COMPAT_nuvoton-layer = "thud"