Blackfin: fix out-of-tree building with ldscripts

Many of the Blackfin board linker scripts are preprocessed, so make sure we
output the linker script into the build tree rather than the source tree.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/board/bf533-stamp/Makefile b/board/bf533-stamp/Makefile
index 21f6ad1..5ae0228 100644
--- a/board/bf533-stamp/Makefile
+++ b/board/bf533-stamp/Makefile
@@ -35,12 +35,11 @@
 OBJS	:= $(addprefix $(obj),$(COBJS))
 SOBJS	:= $(addprefix $(obj),$(SOBJS))
 
-$(LIB):	$(obj).depend $(OBJS) $(SOBJS) u-boot.lds
+$(LIB):	$(obj).depend $(OBJS) $(SOBJS) $(obj)u-boot.lds
 	$(AR) $(ARFLAGS) $@ $(OBJS) $(SOBJS)
 
-u-boot.lds: u-boot.lds.S
-	$(CPP) $(CPPFLAGS) -D__ASSEMBLY__ -P -Ubfin $^ > $@.tmp
-	mv -f $@.tmp $@
+$(obj)u-boot.lds: u-boot.lds.S
+	$(CPP) $(CPPFLAGS) -D__ASSEMBLY__ -P $^ > $@
 
 clean:
 	rm -f $(SOBJS) $(OBJS)