drm/msm: add support to take dsi, dp and dpu snapshot

Add support to take the register snapshot of dsi, dp and dpu
modules.

Signed-off-by: Abhinav Kumar <abhinavk@codeaurora.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/1618606645-19695-7-git-send-email-abhinavk@codeaurora.org


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