xhci: refactor TRB_ENABLE_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_ENABLE_SLOT switch case in
handle_cmd_completion() into a fuction named xhci_handle_cmd_enable_slot().
Signed-off-by: NXenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/host/xhci-ring.c

@@ -1384,6 +1384,16 @@ static int handle_stopped_cmd_ring(struct xhci_hcd *xhci,
 	return cur_trb_is_good;
 }
 
+static void xhci_handle_cmd_enable_slot(struct xhci_hcd *xhci, int slot_id,
+		u32 cmd_comp_code)
+{
+	if (cmd_comp_code == COMP_SUCCESS)
+		xhci->slot_id = slot_id;
+	else
+		xhci->slot_id = 0;
+	complete(&xhci->addr_dev);
+}
+
 static void handle_cmd_completion(struct xhci_hcd *xhci,
 		struct xhci_event_cmd *event)
 {
@@ -1437,11 +1447,8 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 	switch (le32_to_cpu(xhci->cmd_ring->dequeue->generic.field[3])
 		& TRB_TYPE_BITMASK) {
 	case TRB_TYPE(TRB_ENABLE_SLOT):
-		if (GET_COMP_CODE(le32_to_cpu(event->status)) == COMP_SUCCESS)
-			xhci->slot_id = slot_id;
-		else
-			xhci->slot_id = 0;
-		complete(&xhci->addr_dev);
+		xhci_handle_cmd_enable_slot(xhci, slot_id,
+				GET_COMP_CODE(le32_to_cpu(event->status)));
 		break;
 	case TRB_TYPE(TRB_DISABLE_SLOT):
 		if (xhci->devs[slot_id]) {