drm/msm/adreno: Add A306A support

Add support for Adreno 306A GPU what is found in MSM8917 SoC.
This GPU marketing name is Adreno 308.

Signed-off-by: Otto Pflüger <otto.pflueger@abscue.de>
[use internal name of the GPU, reword the commit message]
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Barnabás Czémán <trabarni@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/605403/


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