av1: set skip mode frames properly

There are circumstances where the flag isn't set but the skip mode
frames are. So don't use the inferred bit which has other inputs
when deciding to pass the skip mode frames to the device.

This fixes some decoding bugs on intel av1

libavcodec/av1dec.c

@@ -270,7 +270,9 @@ static void skip_mode_params(AV1DecContext *s)
     int second_forward_idx, second_forward_hint;
     int ref_hint, dist, i;
 
-    if (!header->skip_mode_present)
+    if (header->frame_type == AV1_FRAME_KEY ||
+        header->frame_type == AV1_FRAME_INTRA_ONLY ||
+        !header->reference_select || !seq->enable_order_hint)
         return;
 
     forward_idx  = -1;