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>

board/google/Kconfig

@@ -22,6 +22,13 @@ config TARGET_CHROMEBOOK_LINK
 	  and it provides a 2560x1700 high resolution touch-enabled LCD
 	  display.
 
+config TARGET_CHROMEBOOK_LINK64
+	bool "Chromebook link 64-bit"
+	help
+	  This is the Chromebook Pixel released in 2013. With this config
+	  U-Boot is built as a 64-bit binary. This allows testing while this
+	  feature is being completed.
+
 config TARGET_CHROMEBOX_PANTHER
 	bool "Chromebox panther (not available)"
 	select n

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"

board/google/chromebook_link/MAINTAINERS

@@ -4,3 +4,10 @@ S:	Maintained
 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