USB: xhci: Refactor code to free or cache endpoint rings.

Refactor out the code to cache or free endpoint rings from recently
dropped or disabled endpoints.  This code will be used by a new function
to reset a device and disable all endpoints except control endpoint 0.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 8778135..61747f3 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1233,6 +1233,9 @@
 		struct usb_device *udev, struct usb_host_endpoint *ep,
 		gfp_t mem_flags);
 void xhci_ring_free(struct xhci_hcd *xhci, struct xhci_ring *ring);
+void xhci_free_or_cache_endpoint_ring(struct xhci_hcd *xhci,
+		struct xhci_virt_device *virt_dev,
+		unsigned int ep_index);
 struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
 		bool allocate_completion, gfp_t mem_flags);
 void xhci_free_command(struct xhci_hcd *xhci,