cmd/internal/obj/loong64: adjust the order of class names

cmd/internal/obj/loong64: adjust the order of class names

Change-Id: I0ff9a4f7b4758f44eaedfd821ad80a86b58e55a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/565625
Reviewed-by: Qiqi Huang <huangqiqi@loongson.cn>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: sophie zhao <zhaoxiaolin@loongson.cn>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: abner chenc <chenguoqi@loongson.cn>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>