drm/amd/display: Device flash garbage before get in OS

[Why]
Enabling stream with tg lock makes config settings
pending causing the garbage until tg unlock.

[How]
Keep the original lock mechanism
The driver doesn't lock tg if plane_state is null.
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Chiawen Huang <chiawen.huang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

@@ -110,6 +110,7 @@ void dcn10_lock_all_pipes(struct dc *dc,
 		 */
 		if (pipe_ctx->top_pipe ||
 		    !pipe_ctx->stream ||
+		    !pipe_ctx->plane_state ||
 		    !tg->funcs->is_tg_enabled(tg))
 			continue;