mac80211: Improve confusing comment around tx_info clearing

The comment above the ieee80211_tx_info_clear_status() helper was somewhat
confusing as to which fields it was or wasn't clearing. So replace it by
something that is hopefully more, well, clear.

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220404210108.2684907-1-toke@toke.dk
Signed-off-by: Johannes Berg <johannes.berg@intel.com>