Moved USB Setup Response Dissection into own function

USB Setup Responses are now dissected in their own function.
Before they were dissected inline in the usb_dissect_common()
function.
(just copied code).

Also replaced proto_tree_add_text() with proto_tree_add_item()
for generic setup response data.

Change-Id: Ia3943334cccc0a1813e0c906196307f99561ad21
Reviewed-on: https://code.wireshark.org/review/2959
Reviewed-by: Evan Huus <eapache@gmail.com>