usb: gadget: composite: fill bcdUSB as 0x0320 for SuperSpeed or higher speeds

The USB3CV version 2.1.80 (March 26, 2018) requires all devices
( gen1, gen2, single lane, dual lane) to return the value of 0x0320
in the bcdUSB field

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>