usb: xhci: remove xhci_dbg_ep_rings()

xhci_dbg_ep_rings() isn't used in xhci driver anymore. Remove
it to reduce the module binary size.

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.h

@@ -1933,9 +1933,6 @@ void xhci_dbg_ring_ptrs(struct xhci_hcd *xhci, struct xhci_ring *ring);
 void xhci_dbg_ctx(struct xhci_hcd *xhci, struct xhci_container_ctx *ctx, unsigned int last_ep);
 char *xhci_get_slot_state(struct xhci_hcd *xhci,
 		struct xhci_container_ctx *ctx);
-void xhci_dbg_ep_rings(struct xhci_hcd *xhci,
-		unsigned int slot_id, unsigned int ep_index,
-		struct xhci_virt_ep *ep);
 void xhci_dbg_trace(struct xhci_hcd *xhci, void (*trace)(struct va_format *),
 			const char *fmt, ...);