Add support for ST M29F400BT - part 1

Corresponding to coreboot v1 svn r582.
diff --git a/flash.h b/flash.h
index 2e1f600..286e219 100644
--- a/flash.h
+++ b/flash.h
@@ -32,6 +32,9 @@
 #define WINBOND_ID        0xDA	/* Winbond Manufacture ID code	*/
 #define W_29C020C         0x45	/* Winbond w29c020c device code*/
 
+#define ST_ID       	  0x20	
+#define ST_M29F400BT      0xD5
+
 extern int probe_28sf040 (struct flashchip * flash);
 extern int erase_28sf040 (struct flashchip * flash);
 extern int write_28sf040 (struct flashchip * flash, char * buf);