usb: hub: rename khubd to hub_wq in documentation and comments

USB hub has started to use a workqueue instead of kthread. Let's update
the documentation and comments here and there.

This patch mostly just replaces "khubd" with "hub_wq". There are only few
exceptions where the whole sentence was updated. These more complicated
changes can be found in the following files:

	   Documentation/usb/hotplug.txt
	   drivers/net/usb/usbnet.c
	   drivers/usb/core/hcd.c
	   drivers/usb/host/ohci-hcd.c
	   drivers/usb/host/xhci.c

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/wusbcore/devconnect.c b/drivers/usb/wusbcore/devconnect.c
index 0677139..3f4f5fb 100644
--- a/drivers/usb/wusbcore/devconnect.c
+++ b/drivers/usb/wusbcore/devconnect.c
@@ -329,7 +329,7 @@
 	port->wusb_dev = wusb_dev;
 	port->status |= USB_PORT_STAT_CONNECTION;
 	port->change |= USB_PORT_STAT_C_CONNECTION;
-	/* Now the port status changed to connected; khubd will
+	/* Now the port status changed to connected; hub_wq will
 	 * pick the change up and try to reset the port to bring it to
 	 * the enabled state--so this process returns up to the stack
 	 * and it calls back into wusbhc_rh_port_reset().
@@ -343,7 +343,7 @@
 /*
  * Disconnect a Wireless USB device from its fake port
  *
- * Marks the port as disconnected so that khubd can pick up the change
+ * Marks the port as disconnected so that hub_wq can pick up the change
  * and drops our knowledge about the device.
  *
  * Assumes there is a device connected
@@ -379,7 +379,7 @@
 		wusbhc_gtk_rekey(wusbhc);
 
 	/* The Wireless USB part has forgotten about the device already; now
-	 * khubd's timer will pick up the disconnection and remove the USB
+	 * hub_wq's timer will pick up the disconnection and remove the USB
 	 * device from the system
 	 */
 }