xhci: unify cycle state toggling operation with 'XOR'

Some toggling operation in xHCI driver still use conditional toggling:
ring->cycle_state = (ring->cycle_state ? 0 : 1);

Use XOR to invert the cycle state instead of a conditional toggle to unify
cycle state toggling operation in xHCI driver.
Signed-off-by: NLin Wang <lin.x.wang@intel.com>
Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -238,7 +238,7 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring,
 
 			/* Toggle the cycle bit after the last ring segment. */
 			if (last_trb_on_last_seg(xhci, ring, ring->enq_seg, next)) {
-				ring->cycle_state = (ring->cycle_state ? 0 : 1);
+				ring->cycle_state ^= 1;
 			}
 		}
 		ring->enq_seg = ring->enq_seg->next;
@@ -2809,7 +2809,7 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
 
 			/* Toggle the cycle bit after the last ring segment. */
 			if (last_trb_on_last_seg(xhci, ring, ring->enq_seg, next)) {
-				ring->cycle_state = (ring->cycle_state ? 0 : 1);
+				ring->cycle_state ^= 1;
 			}
 			ring->enq_seg = ring->enq_seg->next;
 			ring->enqueue = ring->enq_seg->trbs;