x86: Save the BIST value on reset

The built in self test value is available in register eax on start-up. Save
it so that it can be accessed later. Unfortunately we must wait until the
global_data is available before we can do this, so there is a little bit of
shuffling to keep it around.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/include/asm/global_data.h b/arch/x86/include/asm/global_data.h
index 3e8e2cd..9eae228 100644
--- a/arch/x86/include/asm/global_data.h
+++ b/arch/x86/include/asm/global_data.h
@@ -17,6 +17,7 @@
 	uint32_t tsc_base_kclocks;	/* Initial tsc as a kclocks value */
 	uint32_t tsc_prev;		/* For show_boot_progress() */
 	void *new_fdt;			/* Relocated FDT */
+	uint32_t bist;			/* Built-in self test value */
 };
 
 #endif