Fix the code to allow a 3rd compound mode

It is possible down the road new compound modes are added in addition to
COMPOUND_AVERAGE and COMPOUND_WEDGE.

Change-Id: I85985d4c104effd34df13845344aac2a08d28019
diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 5ddb4d1..74e159e 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -7513,7 +7513,7 @@
 
     *compmode_wedge_cost = compound_type_cost[mbmi->interinter_compound];
 
-    if (mbmi->interinter_compound)
+    if (mbmi->interinter_compound == COMPOUND_WEDGE)
       *compmode_wedge_cost +=
           av1_cost_literal(get_interinter_wedge_bits(bsize));
   }