drm/msm: Adjust a7xx GBIF debugbus dumping

Use the kgsl-style list of indices, because this is about to change for
a750 and we want to reuse the downstream header directly.
Patchwork: https://patchwork.freedesktop.org/patch/592520/

Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/592520
Signed-off-by: Rob Clark <robdclark@chromium.org>