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/MAINTAINERS b/board/google/chromebook_link/MAINTAINERS
index bc253a2..e7aef53 100644
--- a/board/google/chromebook_link/MAINTAINERS
+++ b/board/google/chromebook_link/MAINTAINERS
@@ -4,3 +4,10 @@
 F:	board/google/chromebook_link/
 F:	include/configs/chromebook_link.h
 F:	configs/chromebook_link_defconfig
+
+CHROMEBOOK LINK 64-bit BOARD
+M:	Simon Glass <sjg@chromium.org>
+S:	Maintained
+F:	board/google/chromebook_link/
+F:	include/configs/chromebook_link.h
+F:	configs/chromebook_link64_defconfig