unix: remove /dev/ptyp* from device node tests on NetBSD
unix: remove /dev/ptyp* from device node tests on NetBSD

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 <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/sys,multiplay/golang-sys,multiplay/golang-sys,multiplay/golang-sys,multiplay/golang-sys,golang/sys,golang/sys