xhci: move dequeue to next valid td instead of past cancelled one

If a ring stops on a TD that is about to be cancelled then the xHC ring
hardware dequeue pointer needs to move past the TD to flush TRBs from
xHC cache.

The TRB after the cancelled TD might be a no-op TRB, or a link TRB.
Moving the dequeue to a link TRB has caused isses on some hosts, and
moving it to a no-op TRB can be an issue for control endpoints as
xhci specification 4.8.3 'Endpoint Context State" states that
The Default Control Endpoint shall return to the Running state when the
Doorbell is rung for the next Setup Stage TD sent to the endpoint.

Solve this by always moving the dequeue pointer to the next valid
TD. If ring is empty and there are no queued TDs then move the dequeue
pointer to the enqueue pointer.
If enqueue points to a link TRB on a empty ring then propagate enqueue
to next segment before pointing dequeue to it.

Note that this patch ended up almost identical to a simplifiaction patch
done earlier by Michal Pecio, see link. That patch was not added due to a
potential, somewhat theoretical issue of moving dequeue backwards.
Turns out improving cancelled control transfers end up with the same code,
and is now worth taking.
Code is very likely subconsciously based the patch by Michal Pecio.

Link: https://lore.kernel.org/linux-usb/20250225125939.7a248e38@foxbook/
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20260806142113.2436238-7-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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