Don't return 0 if error is set to EBADRPC. Found by jsg@ and clang.
Don't return 0 if error is set to EBADRPC. Found by jsg@ and clang.

ok deraadt@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars