drm/msm/dpu: move encoder status to standard encoder debugfs dir

Now as we have standard per-encoder debugfs directory, move DPU encoder
status file to that directory.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/570219/
Link: https://lore.kernel.org/r/20231203115315.1306124-4-dmitry.baryshkov@linaro.org