ppc4xx: Complete DU440 board support

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
diff --git a/Makefile b/Makefile
index 8a888b9..e75a843 100644
--- a/Makefile
+++ b/Makefile
@@ -1206,6 +1206,9 @@
 DU405_config:	unconfig
 	@$(MKCONFIG) $(@:_config=) ppc ppc4xx du405 esd
 
+DU440_config:	unconfig
+	@$(MKCONFIG) $(@:_config=) ppc ppc4xx du440 esd
+
 ebony_config:	unconfig
 	@$(MKCONFIG) $(@:_config=) ppc ppc4xx ebony amcc