drm/msm/dpu: add wb_idx to DRM traces in dpu_encoder

Change the DRM traces to include both the intf_mode
and wb_idx similar to the DRM prints in the previous change.

Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/483528/
Link: https://lore.kernel.org/r/1650984096-9964-20-git-send-email-quic_abhinavk@quicinc.com
[DB: fixed indentation and added wb_idx to the dpu_enc_trigger_flush's TP_ARGS]
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>