usb: set ep_dev async suspend should be later than device_initialize

The dev->power.async_suspend can only be set at the condition of
dev->power.status is DPM_ON. The dev->power.status will be initialized
as DPM_ON at device_initialize.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>