xhci: Fix xhci debugfs devices node disappearance after hibernation

During system resume from hibernation, xhci host is reset, all the
nodes in devices folder are removed in xhci_mem_cleanup function.
Later nodes in /sys/kernel/debug/usb/xhci/* are created again in
function xhci_run, but the nodes already exist, so the nodes still
keep the old ones, finally device nodes in xhci debugfs folder
/sys/kernel/debug/usb/xhci/*/devices/* are disappeared.

This fix removed xhci debugfs nodes before the nodes are re-created,
so all the nodes in xhci debugfs can be re-created successfully.

Fixes: 02b6fdc2 ("usb: xhci: Add debugfs interface for xHCI driver")
Cc: <stable@vger.kernel.org> # v4.15
Signed-off-by: Zhengjun Xing <zhengjun.xing@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.c

@@ -1014,6 +1014,7 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
 
 		xhci_dbg(xhci, "cleaning up memory\n");
 		xhci_mem_cleanup(xhci);
+		xhci_debugfs_exit(xhci);
 		xhci_dbg(xhci, "xhci_stop completed - status = %x\n",
 			    readl(&xhci->op_regs->status));