USB: separate autosuspend from external suspend

This patch (as866) adds new entry points for external USB device
suspend and resume requests, as opposed to internally-generated
autosuspend or autoresume.  It also changes the existing
remote-wakeup code paths to use the new routines, since remote wakeup
is not the same as autoresume.

As part of the change, it turns out to be necessary to do remote
wakeup of root hubs from a workqueue.  We had been using khubd, but it
does autoresume rather than an external resume.  Using the
ksuspend_usb_wq workqueue for this purpose seemed a logical choice.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 82338f4..138252e 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -49,7 +49,8 @@
 
 static int nousb;	/* Disable USB when built into kernel image */
 
-struct workqueue_struct *ksuspend_usb_wq;	/* For autosuspend */
+/* Workqueue for autosuspend and for remote wakeup of root hubs */
+struct workqueue_struct *ksuspend_usb_wq;
 
 #ifdef	CONFIG_USB_SUSPEND
 static int usb_autosuspend_delay = 2;		/* Default delay value,