efi: stub: Pass EFI system table address to U-Boot payload

This updates the EFI stub codes to pass UEFI BIOS's system table
address to U-Boot payload so that U-Boot can utilize it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/efi.h b/include/efi.h
index 7e7c1ca..63017c8 100644
--- a/include/efi.h
+++ b/include/efi.h
@@ -248,6 +248,7 @@
 	EFIET_END,	/* Signals this is the last (empty) entry */
 	EFIET_MEMORY_MAP,
 	EFIET_GOP_MODE,
+	EFIET_SYS_TABLE,
 
 	/* Number of entries */
 	EFIET_MEMORY_COUNT,
@@ -338,6 +339,15 @@
 	} info[];
 };
 
+/**
+ * struct efi_entry_systable - system table passed to U-Boot
+ *
+ * @sys_table:	EFI system table address
+ */
+struct efi_entry_systable {
+	efi_physical_addr_t sys_table;
+};
+
 static inline struct efi_mem_desc *efi_get_next_mem_desc(
 		struct efi_entry_memmap *map, struct efi_mem_desc *desc)
 {