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

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/board/freescale/m5275evb/Makefile b/board/freescale/m5275evb/Makefile
index 5d09afe..ef0b19e 100644
--- a/board/freescale/m5275evb/Makefile
+++ b/board/freescale/m5275evb/Makefile
@@ -23,18 +23,22 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).a
 
 OBJS	= $(BOARD).o mii.o
 
+SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
+OBJS	:= $(addprefix $(obj),$(COBJS))
+SOBJS	:= $(addprefix $(obj),$(SOBJS))
+
 $(LIB):	.depend $(OBJS)
 	$(AR) $(ARFLAGS) $@ $(OBJS)
 
 #########################################################################
 
-.depend:	Makefile $(SOBJS:.o=.S) $(OBJS:.o=.c)
-		$(CC) -M $(CFLAGS) $(SOBJS:.o=.S) $(OBJS:.o=.c) > $@
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
 
-sinclude .depend
+sinclude $(obj).depend
 
 #########################################################################