iwlwifi: fix the reclaimed packet tracking upon flush queue

There's a bug in the currently released firmware version,
the sequence control in the Tx response isn't updated in
all cases. Take it from the packet as a workaround.

Cc: stable@vger.kernel.org
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>