all: gofmt

Gofmt to update doc comments to the new formatting.

For golang/go#51082.

Change-Id: I076031b6613691eefbb0f21739366e3fd2011ec9
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/399356
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>

internal/poly1305/sum_s390x.go

@@ -14,6 +14,7 @@ import (
 // updateVX is an assembly implementation of Poly1305 that uses vector
 // instructions. It must only be called if the vector facility (vx) is
 // available.
+//
 //go:noescape
 func updateVX(state *macState, msg []byte)