xhci: refactor TRB_DISABLE_SLOT case into function

The function that handles xHCI command completion is much too long and
there is need to be broken up into individual functions for each command
completion to improve code readablity.
This patch refactors the code in TRB_DISABLE_SLOT switch case in
handle_cmd_completion() into a fuction named xhci_handle_cmd_disable_slot().
Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/host/xhci-ring.c

@@ -1394,6 +1394,19 @@ static void xhci_handle_cmd_enable_slot(struct xhci_hcd *xhci, int slot_id,
 	complete(&xhci->addr_dev);
 }
 
+static void xhci_handle_cmd_disable_slot(struct xhci_hcd *xhci, int slot_id)
+{
+	struct xhci_virt_device *virt_dev;
+
+	virt_dev = xhci->devs[slot_id];
+	if (!virt_dev)
+		return;
+	if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
+		/* Delete default control endpoint resources */
+		xhci_free_device_endpoint_resources(xhci, virt_dev, true);
+	xhci_free_virt_device(xhci, slot_id);
+}
+
 static void handle_cmd_completion(struct xhci_hcd *xhci,
 		struct xhci_event_cmd *event)
 {
@@ -1451,13 +1464,7 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 				GET_COMP_CODE(le32_to_cpu(event->status)));
 		break;
 	case TRB_TYPE(TRB_DISABLE_SLOT):
-		if (xhci->devs[slot_id]) {
-			if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
-				/* Delete default control endpoint resources */
-				xhci_free_device_endpoint_resources(xhci,
-						xhci->devs[slot_id], true);
-			xhci_free_virt_device(xhci, slot_id);
-		}
+		xhci_handle_cmd_disable_slot(xhci, slot_id);
 		break;
 	case TRB_TYPE(TRB_CONFIG_EP):
 		virt_dev = xhci->devs[slot_id];