Blackfin: fix building after asm-offsets.h intro

Since some of the defines in our config.h use the generated defines, we
need to include the generated header.  This fixes building of the Blackfin
start.S file (where the stack is setup).

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/config.h

@@ -9,6 +9,9 @@
 #ifndef __ASM_BLACKFIN_CONFIG_POST_H__
 #define __ASM_BLACKFIN_CONFIG_POST_H__
 
+/* Some of our defines use this (like CONFIG_SYS_GBL_DATA_ADDR) */
+#include <asm-offsets.h>
+
 #ifndef CONFIG_BFIN_SCRATCH_REG
 # define CONFIG_BFIN_SCRATCH_REG retn
 #endif