x86: Make chromebook_link the default board for coreboot

Change SYS_CONFIG_NAME and DEFAULT_DEVICE_TREE to chromebook_link
which is currently the only real board officially supported to run
U-Boot loaded by coreboot.

Note the symbolic link file chromebook_link.dts is deleted and
link.dts is renamed to chromebook_link.dts.

To avoid multiple definition of video_hw_init, the CONFIG_VIDEO_X86
define needs to be moved to arch/x86/cpu/ivybridge/Kconfig.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/dts/Makefile b/arch/x86/dts/Makefile
index 5525094..97ed884 100644
--- a/arch/x86/dts/Makefile
+++ b/arch/x86/dts/Makefile
@@ -1,5 +1,4 @@
-dtb-y += link.dtb \
-	chromebook_link.dtb \
+dtb-y += chromebook_link.dtb \
 	crownbay.dtb
 
 targets += $(dtb-y)
diff --git a/arch/x86/dts/chromebook_link.dts b/arch/x86/dts/chromebook_link.dts
deleted file mode 120000
index 6f8c5cd..0000000
--- a/arch/x86/dts/chromebook_link.dts
+++ /dev/null
@@ -1 +0,0 @@
-link.dts
\ No newline at end of file
diff --git a/arch/x86/dts/link.dts b/arch/x86/dts/chromebook_link.dts
similarity index 100%
rename from arch/x86/dts/link.dts
rename to arch/x86/dts/chromebook_link.dts