UPSTREAM: dt-bindings: opp: Introduce opp-level bindings

Add opp-level as an additional property in the OPP node to describe
the performance level of the device.

On some SoCs (especially from Qualcomm and MediaTek) this value
is communicated to a remote microprocessor by the CPU, which
then takes some actions (like adjusting voltage values across various
rails) based on the value passed.

Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
(cherry picked from commit cea8e2f3
https://github.com/torvalds/linux.git

)
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>

BUG=b:129558664
TEST=Validate DVFS and schedutil governor
Git-repo: https://git.linaro.org/people/niklas.cassel/kernel.git


Git-commit: a8739f2c0db5b8813ea61148e52965141b8aa537
Signed-off-by: Praveen Koya <pkoya@codeaurora.org>

Change-Id: If55cdb5df45d5e99a328bb52dc7c168e892cb0a5
Signed-off-by: Vamsi Singamsetty <vamssi@codeaurora.org>
Signed-off-by: Khasim Syed Mohammed <khasim.mohammed@linaro.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1664358


Reviewed-by: Zhihong Yu <zhihongyu@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Commit-Queue: Zhihong Yu <zhihongyu@chromium.org>
Tested-by: Zhihong Yu <zhihongyu@chromium.org>