[dev.link] cmd/link: gofmt

I somehow messed up my local environment for the pre-commit hook.
Fix the format.

Change-Id: I6161ad1fce7714e8f311be5315d854f8c9bd7664
Reviewed-on: https://go-review.googlesource.com/c/go/+/227579


Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>