USB: improve runtime remote wakeup settings

This patch (as1362) adjusts the way the USB autosuspend routines
handle remote-wakeup settings.  They aren't supposed to use
device_may_wakeup(); that test is intended only for system sleep, not
runtime power management.  Instead the code checks to see if any
interface drivers need remote wakeup; if they do then it is enabled,
provided the device is capable of it.

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