blackfin: Move `-D__BLACKFIN__' to $(ARCH)_config.mk

Signed-off-by: NShinya Kuribayashi <skuribay@ruby.dti.ne.jp>

blackfin_config.mk

@@ -21,4 +21,4 @@
 # MA 02111-1307 USA
 #
 
-PLATFORM_CPPFLAGS += -DCONFIG_BLACKFIN
+PLATFORM_CPPFLAGS += -DCONFIG_BLACKFIN -D__BLACKFIN__

config.mk

@@ -69,10 +69,6 @@ PLATFORM_CPPFLAGS+= -D__ARM__
 endif
 endif
 
-ifeq ($(ARCH),blackfin)
-PLATFORM_CPPFLAGS+= -D__BLACKFIN__
-endif
-
 ifdef	ARCH
 sinclude $(TOPDIR)/$(ARCH)_config.mk	# include architecture dependend rules
 endif