x86: link: Add a config for 64-bit U-Boot

Add a new board config which uses 64-bit U-Boot. This is not fully
functional but is it a start. Missing features:

- SDRAM sizing
- Booting linux
- EFI support
- SCSI device init
(and others)

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/board/google/chromebook_link/Kconfig b/board/google/chromebook_link/Kconfig
index 5c57945..8999b58 100644
--- a/board/google/chromebook_link/Kconfig
+++ b/board/google/chromebook_link/Kconfig
@@ -1,4 +1,4 @@
-if TARGET_CHROMEBOOK_LINK
+if TARGET_CHROMEBOOK_LINK || TARGET_CHROMEBOOK_LINK64
 
 config SYS_BOARD
 	default "chromebook_link"