drm/msm: Use a7xx family directly in gpu_state

With a7xx, we need to import a new header for each new generation and
switch to a different list of registers, instead of making
backwards-compatible changes. Using the helpers inadvertently made a750
use the a740 list of registers, instead use the family directly to fix
this.

Fixes: f3f8207d ("drm/msm: Add devcoredump support for a750")
Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/607392/


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