soc/amd/stoneyridge: Revert CAR teardown wbinvd

Change the cache-as-ram teardown to use invd instead of wbinvd.
Save the return and recover the call's return address in
chipset_teardown_car.

CAR teardown had been modified to use wbinvd to send CAR contents
to DRAM backing prior to teardown.  This allowed CAR variables,
stack, and local variables to be preserved while running the
AMD_DISABLE_STACK macro.

Using the wbinvd instruction has the side effect of sending all
dirty cache contents to DRAM and not only our CAR data.  This
would likely cause corruption, e.g. during S3 resume.

Stoney Ridge now uses a postcar stage and this is no longer a
requirement.

BUG=b:64768556

Change-Id: I8e6bcb3947f508b1db1a42fd0714bba70074837a
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/20967
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions