AV1 RT: Fix external ref structure setting for speed 5

Speed 5 RT was crashing on ARM as the first non-I frame had no
reference. Fixing the wrong check

Change-Id: I3ceeb35c53fcad38506eb91c95a868e83c9b081d
diff --git a/av1/encoder/encode_strategy.c b/av1/encoder/encode_strategy.c
index d9a15b1..9b973b2 100644
--- a/av1/encoder/encode_strategy.c
+++ b/av1/encoder/encode_strategy.c
@@ -1201,13 +1201,13 @@
 
 #if CONFIG_REALTIME_ONLY
   av1_get_one_pass_rt_params(cpi, &frame_params, *frame_flags);
-  if (cpi->oxcf.speed >= 6 && cm->number_spatial_layers == 1 &&
+  if (cpi->oxcf.speed >= 5 && cm->number_spatial_layers == 1 &&
       cm->number_temporal_layers == 1)
     av1_set_reference_structure_one_pass_rt(cpi, gf_group->index == 0);
 #else
   if (use_one_pass_rt_params) {
     av1_get_one_pass_rt_params(cpi, &frame_params, *frame_flags);
-    if (cpi->oxcf.speed >= 6 && cm->number_spatial_layers == 1 &&
+    if (cpi->oxcf.speed >= 5 && cm->number_spatial_layers == 1 &&
         cm->number_temporal_layers == 1)
       av1_set_reference_structure_one_pass_rt(cpi, gf_group->index == 0);
   }