drm/msm/adreno: Add A702 support

The A702 is a weird mix of 600 and 700 series.. Perhaps even a
testing ground for some A7xx features with good ol' A6xx silicon.
It's basically A610 that's been beefed up with some new registers
and hw features (like APRIV!), that was then cut back in size,
memory bus and some other ways.

Add support for it, tested with QCM2290 / RB1.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/579752/
Signed-off-by: Rob Clark <robdclark@chromium.org>