usb: define USB_SPEED_SUPER_PLUS speed for SuperSpeedPlus USB3.1 devices

Add a new USB_SPEED_SUPER_PLUS device speed, and make sure usb core can
handle the new speed.
In most cases the behaviour is the same as with USB_SPEED_SUPER SuperSpeed
devices. In a few places we add a "Plus" string to inform the user of the
new speed.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/common/common.c

@@ -51,6 +51,7 @@ static const char *const speed_names[] = {
 	[USB_SPEED_HIGH] = "high-speed",
 	[USB_SPEED_WIRELESS] = "wireless",
 	[USB_SPEED_SUPER] = "super-speed",
+	[USB_SPEED_SUPER_PLUS] = "super-speed-plus",
 };
 
 const char *usb_speed_string(enum usb_device_speed speed)