drm/msm: Add devcoredump support for a750

Add an a750 case to the various places where we choose a list of
registers.
Patchwork: https://patchwork.freedesktop.org/patch/592519/



Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/592519


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