wifi: mac80211: introduce ieee80211_refresh_tx_agg_session_timer()

This allows low level drivers to refresh the tx agg session timer, based on
querying stats from the firmware usually. Especially for some mt76 devices
support .net_fill_forward_path would bypass mac80211, which leads to tx BA
session timeout clients that set a timeout in their AddBA response to our
request, even if our request is without a timeout.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Link: https://lore.kernel.org/r/7c3f72eac1c34921cd84a462e60d71e125862152.1676616450.git.ryder.lee@mediatek.com


[slightly clarify commit message, add note about RCU]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>