cmd/internal/obj: remove redundant cnames on loong64

cmd/internal/obj: remove redundant cnames on loong64

Change-Id: I5aa6328a12e74b2801ab60b5a5bb8571d382d5ef
Reviewed-on: https://go-review.googlesource.com/c/go/+/425301
Reviewed-by: xiaodong liu <teaofmoli@gmail.com>
Reviewed-by: Meidan Li <limeidan@loongson.cn>
Reviewed-by: WANG Xuerui <git@xen0n.name>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
Auto-Submit: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>