usb: xhci: cleanup cmd_completion in xhci_virt_device

cmd_completion in struct xhci_virt_device is legacy. With command
structure and command queue introduced in xhci, cmd_completion is
not used any more. This patch removes it.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-mem.c

@@ -1032,7 +1032,6 @@ int xhci_alloc_virt_device(struct xhci_hcd *xhci, int slot_id,
 		goto fail;
 	dev->num_rings_cached = 0;
 
-	init_completion(&dev->cmd_completion);
 	dev->udev = udev;
 
 	/* Point to output device context in dcbaa. */

drivers/usb/host/xhci.h

@@ -999,7 +999,6 @@ struct xhci_virt_device {
 	int				num_rings_cached;
 #define	XHCI_MAX_RINGS_CACHED	31
 	struct xhci_virt_ep		eps[31];
-	struct completion		cmd_completion;
 	u8				fake_port;
 	u8				real_port;
 	struct xhci_interval_bw_table	*bw_table;