drm/msm/dpu: Mark various data tables as const

These structures look like a bunch of data tables that aren't going to
change after boot. Let's move them to the const RO section of memory so
that they can't be modified at runtime on modern machines.

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