ppc4xx: HCU4/5. Fix make O=../xx

Signed-off-by: Niklaus Giger <niklaus.giger@netstal.com>
diff --git a/Makefile b/Makefile
index 0f6cc59..b3a1d2f 100644
--- a/Makefile
+++ b/Makefile
@@ -1225,9 +1225,11 @@
 	@$(MKCONFIG) $(@:_config=) ppc ppc4xx g2000
 
 hcu4_config:	unconfig
+	@mkdir -p $(obj)board/netstal/common
 	@$(MKCONFIG) $(@:_config=) ppc ppc4xx hcu4 netstal
 
 hcu5_config:	unconfig
+	@mkdir -p $(obj)board/netstal/common
 	@$(MKCONFIG) $(@:_config=) ppc ppc4xx hcu5 netstal
 
 HH405_config:	unconfig