Blackfin: enable --gc-sections

Start building all Blackfin boards with -ffunction-sections/-fdata-sections
and linking with --gc-sections.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/cpu/blackfin/Makefile b/cpu/blackfin/Makefile
index b4049ff..1378fd1 100644
--- a/cpu/blackfin/Makefile
+++ b/cpu/blackfin/Makefile
@@ -47,6 +47,7 @@
 
 # make sure our initcode (which goes into LDR) does not
 # have relocs or external references
+$(obj)initcode.o: CFLAGS += -fno-function-sections -fno-data-sections
 READINIT = env LC_ALL=C $(CROSS_COMPILE)readelf -s $<
 check_initcode: $(obj)initcode.o
 ifneq ($(CONFIG_BFIN_BOOT_MODE),BFIN_BOOT_BYPASS)