Follow up for CL 80615

The NetBSD 8.0 builders don't seem to have these device nodes either.
Just remove them entirely.

Change-Id: Ib729574ed119f9ec78b06124ba4a5d9bbc74bf4d
Reviewed-on: https://go-review.googlesource.com/81015
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>