Correct the xHCI code to handle stalls on USB endpoints.  We need to move
the endpoint ring's dequeue pointer past the stalled transfer, or the HW
will try to restart the transfer the next time the doorbell is rung.

Don't attempt to clear a halt on an endpoint if we haven't seen a stalled
transfer for it.  The USB core will attempt to clear a halt on all
endpoints when it selects a new configuration.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>