drm/msm/dsi: add DSI config for sm8150 and sm8250

This allows DSI driver to work with sm8150 and sm8250. The sdm845 config
is re-used as the config is the same.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> (SM8250)
Signed-off-by: Rob Clark <robdclark@chromium.org>