dt-bindings: arm: msm: Add SAW2 for MSM8226

Add the dt-binding compatible in the SPM AVS Wrapper 2 (SAW2) for the
MSM8226 SoC platform.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bartosz Dudziak <bartosz.dudziak@snejp.pl>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210612205335.9730-2-bartosz.dudziak@snejp.pl