drm/amd/display: skip phantom pipes when checking for pending flip

[Why&How]
Phantom pipes are not programmed fully to hardware and hence we should
not expect a flip completion.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>

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

@@ -1205,7 +1205,7 @@ static void wait_for_no_pipes_pending(struct dc *dc, struct dc_state *context)
 		int count = 0;
 		struct pipe_ctx *pipe = &context->res_ctx.pipe_ctx[i];
 
-		if (!pipe->plane_state)
+		if (!pipe->plane_state || pipe->stream->mall_stream_config.type == SUBVP_PHANTOM)
 			continue;
 
 		/* Timeout 100 ms */