When enabling a device' wakeup capability, a wakeup source
is created for the device automatically. But the wakeup source
is not unregistered when disabling the device' wakeup capability.

This results in zombie wakeup sources, after devices/drivers are unregistered.
Signed-off-by: NZhang Rui <rui.zhang@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>