drm/msm/adreno: change adreno_is_* functions to accept const argument

All adreno_is_*() functions do not modify their argument in any way, so
they can be changed to accept const struct adreno_gpu pointer.

Suggested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/531706/


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