cmd/compile: remove unneeded calls to typecheck in noder2

Remove unneeded calls to typecheck in noder2 associated with g.use() and
g.obj(). These routines are already setting the types2-derived type
correctly for ONAME nodes, and there is no typechecker1-related
transformations related to ONAME nodes, other than making sure that
newly created closure variables have their type set.

Tested through normal -G=3 testing in all.bash (all of go/tests).

Change-Id: I1b790ab9948959685fca3a768401458201833671
Reviewed-on: https://go-review.googlesource.com/c/go/+/303029


Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Trust: Dan Scales <danscales@google.com>