drm/msm/disp: Use plane debug print helper

Use the DPU_DEBUG_PLANE() helper to print the plane number instead of
open coding it.

Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Abhinav Kumar <abhinavk@codeaurora.org>
Cc: Kuogee Hsieh <khsieh@codeaurora.org>
Cc: aravindh@codeaurora.org
Cc: Sean Paul <sean@poorly.run>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20210430193104.1770538-6-swboyd@chromium.org


Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>