drm/msm/a6xx: Add A740 support

drm/msm/a6xx: Add A740 support

A740 builds upon the A730 IP, shuffling some values and registers
around. More differences will appear when things like BCL are
implemented.

adreno_is_a740_family is added in preparation for more A7xx GPUs,
the logic checks will be valid resulting in smaller diffs.

Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> # sm8450
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/559291/
Signed-off-by: Rob Clark <robdclark@chromium.org>