cmd/compile: use ONAME node directly from generated hash func

cmd/compile: use ONAME node directly from generated hash func

This reverts CL 468879

CL 469017 marked type eq/hash functions as non-inlineable, so this
change won't cause ICE anymore.

Updates #58572

Change-Id: I3e6ec9ba2217102693acd1848a0eba0886dc9fda
Reviewed-on: https://go-review.googlesource.com/c/go/+/469018
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>