iwlwifi: mvm: update txq metadata to current owner

When a TXQ's owner is changed, the FW is indeed notified, but
the driver doesn't update the current metadata to reflect the
owner change. Fix that.

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