Revert "Revert "BACKPORT: x86/i915: Avoid keeping waitboost active for signalling thread.""

This reverts commit b07be3dcaa95258473736042c4b5ba2cb92dea71.

BUG=b:130638275, b:131723850
TEST=Build and boot on nocturne. Make sure GPU frequency is low when
     running camera app.

Change-Id: Ide0dd967c4f91c6f17beaa5aa3bb9f51a6e60671
Signed-off-by: Ricky Liang <jcliang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1657491
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
(cherry picked from commit 7b48e5ab1c017f55a34034829f66647a447da913)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1737910
8 files changed