Blackfin: global_data.h: make pull in needed headers

We need the definition of bd_t in this header, so pull in asm/u-boot.h.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>

include/asm-blackfin/global_data.h

@@ -28,6 +28,8 @@
 #ifndef	__ASM_GBL_DATA_H
 #define __ASM_GBL_DATA_H
 
+#include <asm/u-boot.h>
+
 /*
  * The following data structure is placed in some memory wich is
  * available very early after boot (like DPRAM on MPC8xx/MPC82xx, or