usb: gadget: enable super speed plus

Enable Super speed plus in configfs to support USB3.1 Gen2.
This ensures that when a USB gadget is plugged in, it is
enumerated as Gen 2 and connected at 10 Gbps if the host and
cable are capable of it.

Many in-tree gadget functions (fs, midi, acm, ncm, mass_storage,
etc.) already have SuperSpeed Plus support.

Tested: plugged gadget into Linux host and saw:
[284907.385986] usb 8-2: new SuperSpeedPlus Gen 2 USB device number 3 using xhci_hcd

Tested-by: Lorenzo Colitti <lorenzo@google.com>
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: taehyun.cho <taehyun.cho@samsung.com>
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Link: https://lore.kernel.org/r/20210106154625.2801030-1-lorenzo@google.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: cth2996

drivers/usb/gadget/configfs.c

@@ -1543,7 +1543,7 @@ static const struct usb_gadget_driver configfs_driver_template = {
 	.suspend	= configfs_composite_suspend,
 	.resume		= configfs_composite_resume,
 
-	.max_speed	= USB_SPEED_SUPER,
+	.max_speed	= USB_SPEED_SUPER_PLUS,
 	.driver = {
 		.owner          = THIS_MODULE,
 		.name		= "configfs-gadget",
@@ -1583,7 +1583,7 @@ static struct config_group *gadgets_make(
 	gi->composite.unbind = configfs_do_nothing;
 	gi->composite.suspend = NULL;
 	gi->composite.resume = NULL;
-	gi->composite.max_speed = USB_SPEED_SUPER;
+	gi->composite.max_speed = USB_SPEED_SUPER_PLUS;
 
 	spin_lock_init(&gi->spinlock);
 	mutex_init(&gi->lock);