Blackfin: move CONFIG_BFIN_CPU back to board config.h

This is a revert of 821ad16fa9900c as Wolfgang doesn't like the new code.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/config.mk b/arch/blackfin/config.mk
index 4102c6f..95cf7db 100644
--- a/arch/blackfin/config.mk
+++ b/arch/blackfin/config.mk
@@ -25,6 +25,13 @@
 
 STANDALONE_LOAD_ADDR = 0x1000 -m elf32bfin
 
+ifeq ($(CONFIG_BFIN_CPU),)
+CONFIG_BFIN_CPU := \
+	$(shell awk '$$2 == "CONFIG_BFIN_CPU" { print $$3 }' \
+		$(src)include/configs/$(BOARD).h)
+else
+CONFIG_BFIN_CPU := $(strip $(subst ",,$(CONFIG_BFIN_CPU)))
+endif
 CONFIG_BFIN_BOOT_MODE := $(strip $(subst ",,$(CONFIG_BFIN_BOOT_MODE)))
 
 PLATFORM_RELFLAGS += -ffixed-P3 -fomit-frame-pointer -mno-fdpic
@@ -34,7 +41,6 @@
 LDFLAGS += -m elf32bfin
 PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections
 
-PLATFORM_CPPFLAGS += -DBFIN_CPU='"$(CONFIG_BFIN_CPU)"'
 PLATFORM_RELFLAGS += -mcpu=$(CONFIG_BFIN_CPU)
 
 ifneq ($(CONFIG_BFIN_BOOT_MODE),BFIN_BOOT_BYPASS)