Fixes a mismatch introduced in a previous patch

Fixes a mismatch introdcuded with ext-inter + motion-var in
https://aomedia.googlesource.com/aom/+/42d9610a797dbc778797c04445578eba514d4099

Change-Id: I9d357b6db8fdbfccc7d95aaa196d5d0574ef431b
diff --git a/av1/decoder/decodemv.c b/av1/decoder/decodemv.c
index 32463d4..4872ef6 100644
--- a/av1/decoder/decodemv.c
+++ b/av1/decoder/decodemv.c
@@ -1944,6 +1944,7 @@
 #endif  // CONFIG_MOTION_VAR || CONFIG_WARPED_MOTION
 
 #if CONFIG_EXT_INTER
+  mbmi->interinter_compound_data.type = COMPOUND_AVERAGE;
   if (cm->reference_mode != SINGLE_REFERENCE &&
       is_inter_compound_mode(mbmi->mode)
 #if CONFIG_MOTION_VAR || CONFIG_WARPED_MOTION