Revert "usb: gadget: composite: dequeue cdev->req before free it in composite_dev_cleanup"

This reverts commit f2267089.

That commit causes more problem than fixes. Firstly, kfree()
should be called after usb_ep_dequeue() and secondly, the way
things are, we will try to dequeue a request that has already
completed much more frequently than one which is pending.

Cc: Li Jun <b47624@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Cc: stable <stable@vger.kernel.org> # 3.17
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>