xhci: hub: export symbol on xhci_hub_control

XHCI host drivers may override the default xhci_hub_control() with
their own device specific function. To allow these host drivers to
call the xhci_hub_control() function from within their own
hub_control() callback and be built as a module, export the symbol
for xhci_hub_control.

Signed-off-by: Jim Lin <jilin@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20221111101813.32482-3-jilin@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-hub.c

@@ -1623,6 +1623,7 @@ error:
 	spin_unlock_irqrestore(&xhci->lock, flags);
 	return retval;
 }
+EXPORT_SYMBOL_GPL(xhci_hub_control);
 
 /*
  * Returns 0 if the status hasn't changed, or the number of bytes in buf.