Move this over to use a writer file, moving the code from the x86
implementation.
There is no need to store a separate variable since we can simply access
the ACPI context.
With this, the original monolithic x86 function for writing ACPI tables
is gone.
Note that QEMU has its own implementation.
Signed-off-by: Simon Glass <sjg@chromium.org>
9d2adca8c3