USB: convert to the runtime PM framework

This patch (as1329) converts the USB stack over to the PM core's
runtime PM framework.  This involves numerous changes throughout
usbcore, especially to hub.c and driver.c.  Perhaps the most notable
change is that CONFIG_USB_SUSPEND now depends on CONFIG_PM_RUNTIME
instead of CONFIG_PM.

Several fields in the usb_device and usb_interface structures are no
longer needed.  Some code which used to depend on CONFIG_USB_PM now
depends on CONFIG_USB_SUSPEND (requiring some rearrangement of header
files).

The only visible change in behavior should be that following a system
sleep (resume from RAM or resume from hibernation), autosuspended USB
devices will be resumed just like everything else.  They won't remain
suspended.  But if they aren't in use then they will naturally
autosuspend again in a few seconds.

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