x86: Tidy up use of CONFIG_ACPIGEN

This is enabled for quite a few boards which don't create ACPI tables.
Tidy this up by dropping the option for some boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/chromebook_link64_defconfig b/configs/chromebook_link64_defconfig
index 7059be8..a575437 100644
--- a/configs/chromebook_link64_defconfig
+++ b/configs/chromebook_link64_defconfig
@@ -64,6 +64,7 @@
 CONFIG_TFTP_TSIZE=y
 CONFIG_REGMAP=y
 CONFIG_SYSCON=y
+# CONFIG_ACPIGEN is not set
 CONFIG_CPU=y
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_INTEL=y