mterp: Placeholder support for invoke-polymorphic

Force the mterp assembly interpreters to fall back to the
reference switch interpreter for invoke-polymorphic and
invoke-polymorphic-range while those new opcodes are under
development.

Test: test-art-host

Change-Id: I6167432164bd869c91d0804521d5edc9549f622e
diff --git a/runtime/interpreter/mterp/config_mips64 b/runtime/interpreter/mterp/config_mips64
index aafd248..7643a48 100644
--- a/runtime/interpreter/mterp/config_mips64
+++ b/runtime/interpreter/mterp/config_mips64
@@ -286,8 +286,8 @@
     # op op_unused_f7 FALLBACK
     # op op_unused_f8 FALLBACK
     # op op_unused_f9 FALLBACK
-    # op op_unused_fa FALLBACK
-    # op op_unused_fb FALLBACK
+    op op_invoke_polymorphic FALLBACK
+    op op_invoke_polymorphic_range FALLBACK
     # op op_unused_fc FALLBACK
     # op op_unused_fd FALLBACK
     # op op_unused_fe FALLBACK