Cleanup: fix out-of-tree building for some boards

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/board/ms7720se/Makefile b/board/ms7720se/Makefile
index 236959c..0288bed 100644
--- a/board/ms7720se/Makefile
+++ b/board/ms7720se/Makefile
@@ -27,11 +27,15 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).a
 
 OBJS	:= ms7720se.o
 SOBJS	:= lowlevel_init.o
 
+SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
+OBJS	:= $(addprefix $(obj),$(COBJS))
+SOBJS	:= $(addprefix $(obj),$(SOBJS))
+
 $(LIB):	$(OBJS) $(SOBJS)
 	$(AR) $(ARFLAGS) $@ $(OBJS) $(SOBJS)
 
@@ -43,9 +47,9 @@
 
 #########################################################################
 
-.depend:	Makefile $(SOBJS:.o=.S) $(OBJS:.o=.c)
-		$(CC) -M $(CPPFLAGS) $(SOBJS:.o=.S) $(OBJS:.o=.c) > $@
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
 
--include .depend
+sinclude $(obj).depend
 
 #########################################################################