usb: host: xhci: remove incorrect comment about mutex

The comment stating that xhci_setup_device() is protected by the address
mutex is not true since
commit 6fecd4f2a58c ("USB: separate usb_address0 mutexes for each bus")
as xhci handles two buses.

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

drivers/usb/host/xhci.c

@@ -3764,8 +3764,6 @@ disable_slot:
 /*
  * Issue an Address Device command and optionally send a corresponding
  * SetAddress request to the device.
- * We should be protected by the usb_address0_mutex in hub_wq's hub_port_init,
- * so we should only issue and wait on one address command at the same time.
  */
 static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
 			     enum xhci_setup_dev setup)