reformat dissect_usb_setup_get_descriptor_response()

Change-Id: I8004c4fd6e9cac3615d27b375229a79d01dfcd68
Reviewed-on: https://code.wireshark.org/review/3733
Reviewed-by: Martin Kaiser <wireshark@kaiser.cx>
Tested-by: Martin Kaiser <wireshark@kaiser.cx>