wifi: ath9k: debug.h: fix kernel-doc bad lines and struct ath_tx_stats

wifi: ath9k: debug.h: fix kernel-doc bad lines and struct ath_tx_stats

Repair "bad line" warnings by starting each line with " *".
Add or correct kernel-doc entries for missing struct members in
struct ath_tx_stats.

Warning: ../drivers/net/wireless/ath/ath9k/debug.h:144 bad line:
  may have had errors.
Warning: ../drivers/net/wireless/ath/ath9k/debug.h:146 bad line:
  may have had errors.
Warning: ../drivers/net/wireless/ath/ath9k/debug.h:156 bad line:
  Valid only for:
Warning: ../drivers/net/wireless/ath/ath9k/debug.h:157 bad line:
  - non-aggregate condition.
Warning: ../drivers/net/wireless/ath/ath9k/debug.h:158 bad line:
  - first packet of aggregate.
Warning: drivers/net/wireless/ath/ath9k/debug.h:191 struct member
 'xretries' not described in 'ath_tx_stats'
Warning: drivers/net/wireless/ath/ath9k/debug.h:191 struct member
 'data_underrun' not described in 'ath_tx_stats'
Warning: drivers/net/wireless/ath/ath9k/debug.h:191 struct member
 'delim_underrun' not described in 'ath_tx_stats'

Fixes: 99c15bf575b1 ("ath9k: Report total tx/rx bytes and packets in debugfs.")
Fixes: fec247c0d5bf ("ath9k: Add debug counters for TX")
Fixes: 5a6f78afdabe ("ath9k: show excessive-retry MPDUs in debugfs")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20251117020304.448687-1-rdunlap@infradead.org
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>