vboot: remove vboot_audio.c and friends

No longer used with new vboot UI; remove.
(Missed this in the prior removal of legacy UI code.)

BUG=b:167643628, chromium:968464
TEST=make clean && make runtests
BRANCH=none

Signed-off-by: Joel Kitching <kitching@google.com>
Change-Id: I01383071dee6257921547302fe4a2977b3521195
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2641342
Tested-by: Joel Kitching <kitching@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
7 files changed