Blackfin: update sparse flags for latest upstream changes

Mainline version of git merged support for Blackfin parts, but we now
need to propagate the gcc arch define to make it work.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>

arch/blackfin/Makefile

@@ -101,9 +101,8 @@ KBUILD_CFLAGS += -mcpu=$(cpu-y)-$(rev-y)
 KBUILD_AFLAGS += -mcpu=$(cpu-y)-$(rev-y)
 
 # - we utilize the silicon rev from the toolchain, so move it over to the checkflags
-# - the l1_text attribute is Blackfin specific, so fake it out as used to kill warnings
 CHECKFLAGS_SILICON = $(shell echo "" | $(CPP) $(KBUILD_CFLAGS) -dD - 2>/dev/null | awk '$$2 == "__SILICON_REVISION__" { print $$3 }')
-CHECKFLAGS += -D__SILICON_REVISION__=$(CHECKFLAGS_SILICON) -Dl1_text=__used__
+CHECKFLAGS += -D__SILICON_REVISION__=$(CHECKFLAGS_SILICON) -D__bfin__
 
 head-y   := arch/$(ARCH)/kernel/init_task.o