Advance the image iterator correctly

This patch fixed the image iterator bug that broke the lightfield decoding.

BUG=aomedia:2013

Change-Id: I96835226c71dc724e077a838bfbc7fd7dd4ccc7b

av1/av1_dx_iface.c

diff --git a/av1/av1_dx_iface.c b/av1/av1_dx_iface.c
index aa2987d..c4abf65 100644
--- a/av1/av1_dx_iface.c
+++ b/av1/av1_dx_iface.c
@@ -672,6 +672,7 @@
           yuvconfig2image(&ctx->img, sd, frame_worker_data->user_priv);
 
           if (!pbi->ext_tile_debug && cm->large_scale_tile) {
+            *index += 1;  // Advance the iterator to point to the next image
             img = &ctx->img;
             img->img_data = pbi->tile_list_output;
             img->sz = pbi->tile_list_size;