iwlwifi: mvm: support txq tid owner change

Every active TXQ is assigned to a TID given through the
SCD_CONFIG_CMD, and acts as an identifier in the FW. However,
there may be cases this ownership needs to be changed.

For example, in the following scenario:
 1. TID x is owner of a queue
 2. Due to a shortage of queues, TID y and z share with x
 3. TID x becomes inactive and needs to be removed from the
    shared queue.
In this scenario, if another queue is freed and traffic on x
continues, we can't allocate it a new queue as long as it is
the owner of the first queue.

Support moving ownership of a TXQ to a different TID (same
STA) without stopping the queue.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>