Blackfin: unify u-boot linker scripts

All the Blackfin linker scripts were duplicated across the board dirs with
no difference save from the semi-often used ENV_IS_EMBEDDED option.  So
unify all of them in the lib_blackfin/ dir and for the few boards that
need to embedded the environment directly, add a LDS_BOARD_TEXT define for
them to customize via their board config file.  This is much simpler than
forcing them to duplicate the rest of the linker script.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/board/ibf-dsp561/Makefile b/board/ibf-dsp561/Makefile
index daebb74..bfeaf79 100644
--- a/board/ibf-dsp561/Makefile
+++ b/board/ibf-dsp561/Makefile
@@ -35,12 +35,9 @@
 OBJS	:= $(addprefix $(obj),$(COBJS-y))
 SOBJS	:= $(addprefix $(obj),$(SOBJS-y))
 
-$(LIB):	$(obj).depend $(OBJS) $(SOBJS) $(obj)u-boot.lds
+$(LIB):	$(obj).depend $(OBJS) $(SOBJS)
 	$(AR) $(ARFLAGS) $@ $(OBJS) $(SOBJS)
 
-$(obj)u-boot.lds: u-boot.lds.S
-	$(CPP) $(CPPFLAGS) -D__ASSEMBLY__ -P $^ > $@
-
 clean:
 	rm -f $(SOBJS) $(OBJS)