[JVMCI] invalid code in PushLocalFrame event message

The event logged[1] when PushLocalFrame fails on initializing a JVMCIEnv uses the wrong variable for the PushLocalFrame error return value. It should be `result` instead of `_init_error`.

[1] https://github.com/openjdk/jdk/blob/c75c38871ee7b5c9f7f0c195d649c16967f786bb/src/hotspot/share/jvmci/jvmciEnv.cpp#L192