drm/msm/dpu: add SM8250 to hw catalog

This brings up basic video mode functionality for SM8250 DPU. Command mode
and dual mixer/intf configurations are not working, future patches will
address this. Scaler functionality and multiple planes is also untested.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Rob Clark <robdclark@chromium.org>