iwlwifi: mvm: process ba-notifications also when sta rcu is invalid

iwlwifi: mvm: process ba-notifications also when sta rcu is invalid

The the driver prevents new Tx from being sent during the remove-station
flow is by invalidating the fw_id_to_mac_id rcu of that station.

However, if there was any Tx still in-flight (tx-cmd was sent but the
ba-notif wasn't received yet) the ba-response to those frames is simply
ignored without actually reclaiming anything. This later causes the
driver to think that that some of the station's queues aren't empty when
in practice they are which causes errors in the station remove flow.

Fix this by performing the tx-reclaim also if the rcu is invalid. any DB
that can't be updated due to this is not very important at this stage
since the station is about to be removed soon anyways.

Signed-off-by: Naftali Goldstein <naftali.goldstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200926002540.72c604b4eda9.I21e75b31a9401870d18747355d4f4305b2fe1db8@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>