further rearranged control URB request conditionals

combined 2 sections for dissecting non-standard requests into 1

Change-Id: I181346a69e2f96ff47b82f82d3aa69846c45614f
Reviewed-on: https://code.wireshark.org/review/3849
Reviewed-by: Michael Mann <mmann78@netscape.net>
Petri-Dish: Michael Mann <mmann78@netscape.net>
Reviewed-by: Anders Broman <a.broman58@gmail.com>