mac80211: minstrel_ht: set default tx aggregation timeout to 0

The value 5000 was put here with the addition of the timeout field to
ieee80211_start_tx_ba_session. It was originally added in mac80211 to
save resources for drivers like iwlwifi, which only supports a limited
number of concurrent aggregation sessions.

Since iwlwifi does not use minstrel_ht and other drivers don't need
this, 0 is a better default - especially since there have been
recent reports of aggregation setup related issues reproduced with
ath9k. This should improve stability without causing any adverse
effects.

Cc: stable@vger.kernel.org
Acked-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>