usb: gadget: f_mass_storage: Enable SuperSpeedPlus

Enable superspeed plus configuration for the mass storage gadget.

The mass storage function doesn't do anything special for
SuperSpeedPlus. Just pass in the same SuperSpeed descriptors for
SuperSpeedPlus.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>