[dev.regabi] cmd/compile: rename NameOffsetExpr to LinksymOffsetExpr

[dev.regabi] cmd/compile: rename NameOffsetExpr to LinksymOffsetExpr

Updates #43737

[git-generate]

cd src/cmd/compile/internal/ir

rf '
  mv NameOffsetExpr LinksymOffsetExpr
  mv ONAMEOFFSET OLINKSYMOFFSET
'

go generate

Change-Id: I8c6b8aa576e88278c0320d16bb2e8e424a15b907
Reviewed-on: https://go-review.googlesource.com/c/go/+/284120
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>