cmd/compile/internal/types: change NewTypeParam to match New{Basic,Named}

cmd/compile/internal/types: change NewTypeParam to match New{Basic,Named}

NewBasic and NewNamed take an Object (i.e., *ir.Name), so that callers
don't need to call SetNod. This CL changes NewTypeParam to follow the
same convention. Following up on recent Ntype removal, this allows
getting rid of Type.SetNod entirely.

While here, Type.SetSym is unused too.

Change-Id: Ibe0f5747e2ab4a9512b65142b6d3006704b60bd3
Reviewed-on: https://go-review.googlesource.com/c/go/+/405654
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>