Cleanup out-or-tree building for some boards (.depend)

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/board/netstar/Makefile b/board/netstar/Makefile
index 88da2b9..8d911b8 100644
--- a/board/netstar/Makefile
+++ b/board/netstar/Makefile
@@ -84,7 +84,7 @@
 		$(obj)crcek.bin
 
 distclean:	clean
-	rm -f $(LIB) core *.bak .depend
+	rm -f $(LIB) core *.bak $(obj).depend
 
 #########################################################################