usb: show speed "10000" in sysfs for USB 3.1 SuperSpeedPlus devices

BugLink: http://bugs.launchpad.net/bugs/1519623



The same way as SuperSpeed devices show "5000" as device speed we wan't to
show "10000" as the default speed for SuperSpeedPlus devices in sysfs.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit b2316645)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>