x86: acpi: Support external GNVS tables

At present U-Boot puts a magic number in the ASL for the GNVS table and
searches for it later.

Add a Kconfig option to use a different approach, where the ASL files
declare the table as an external symbol. U-Boot can then put it wherever
it likes, without any magic numbers or searching.

Signed-off-by: Simon Glass <sjg@chromium.org>
4 files changed