xhci: allow TRACE to work with EVENT ring dequeue

inc_deq() currently bails earlier for EVENT rings than the common return
point of the function, due to the fact that EVENT rings do not have
link TRBs. The unfortunate side effect of this is that the very useful
trace_xhci_inc_deq() function is not called/usable for EVENT ring
debug.

This patch provides a refactor by removing the multiple return exit
points into a single return which additionally allows for all rings to
use the trace function.

Signed-off-by: Adam Wallis <awallis@codeaurora.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -171,13 +171,13 @@ static void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring)
 	if (ring->type == TYPE_EVENT) {
 		if (!last_trb_on_seg(ring->deq_seg, ring->dequeue)) {
 			ring->dequeue++;
-			return;
+			goto out;
 		}
 		if (last_trb_on_ring(ring, ring->deq_seg, ring->dequeue))
 			ring->cycle_state ^= 1;
 		ring->deq_seg = ring->deq_seg->next;
 		ring->dequeue = ring->deq_seg->trbs;
-		return;
+		goto out;
 	}
 
 	/* All other rings have link trbs */
@@ -190,6 +190,7 @@ static void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring)
 		ring->dequeue = ring->deq_seg->trbs;
 	}
 
+out:
 	trace_xhci_inc_deq(ring);
 
 	return;