USB feature selectors now per USB 3.1 spec

previously per USB 2 spec.

Change-Id: Ifb25614785bcaf80148c32938f966c8cdded6be2
Reviewed-on: https://code.wireshark.org/review/4087
Reviewed-by: Evan Huus <eapache@gmail.com>
Petri-Dish: Evan Huus <eapache@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>