drm/msm/adreno: Use adreno_is_revn for A690

The adreno_is_revn rework came at the same time as A690 introduction
and that resulted in it not covering all cases. Fix it.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/542754/


Signed-off-by: Rob Clark <robdclark@chromium.org>