drm/amd/display: add log for automated test

[Why&How]
Add log for easier debug purposes.
Signed-off-by: NQingqing Zhuo <qingqing.zhuo@amd.com>
Reviewed-by: NNicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: NAnson Jacob <Anson.Jacob@amd.com>
Tested-by: NDan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -2902,6 +2902,10 @@ static void dp_test_send_link_test_pattern(struct dc_link *link)
 
 	if (requestColorDepth != COLOR_DEPTH_UNDEFINED
 			&& pipe_ctx->stream->timing.display_color_depth != requestColorDepth) {
+		DC_LOG_DEBUG("%s: original bpc %d, changing to %d\n",
+				__func__,
+				pipe_ctx->stream->timing.display_color_depth,
+				requestColorDepth);
 		pipe_ctx->stream->timing.display_color_depth = requestColorDepth;
 		dp_update_dsc_config(pipe_ctx);
 	}