Make opcode 00ff be called "dispatch-ff".

With this change, it's still implemented as an unused opcode, but
it's now ready for its new life!

Change-Id: Ic70d311704925067e47d87b657d133a792144e65
diff --git a/vm/compiler/codegen/arm/CodegenDriver.c b/vm/compiler/codegen/arm/CodegenDriver.c
index 55fee0e..0c5b617 100644
--- a/vm/compiler/codegen/arm/CodegenDriver.c
+++ b/vm/compiler/codegen/arm/CodegenDriver.c
@@ -1338,7 +1338,7 @@
         case OP_UNUSED_73:
         case OP_UNUSED_79:
         case OP_UNUSED_7A:
-        case OP_UNUSED_FF:
+        case OP_DISPATCH_FF:
             LOGE("Codegen: got unused opcode 0x%x\n",dalvikOpcode);
             return true;
         case OP_NOP: