drm/msm/dpu: merge two CRTC debugfs dirs

For each CRTC we are creating two different debugfs directories one
using crtc index (created automatically for the CRC files) and another
one using CRTC name/object ID (for state and status files).

This can be confusing, so move our custom files to crtc->debugfs_entry,
effetively merging two debugfs dirs.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Tested-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/518065/
Link: https://lore.kernel.org/r/20230112053659.1361298-1-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>