ath10k: fix per station tx bit rate reporting

ath10k: fix per station tx bit rate reporting

Not clearing the previous tx bit rate status
results in a ambigous tx bit rate reporting to
mac80211/cfg80211, for example the previous bit
rate status would have been marked as legacy rate
, while the current rate would have been an HT/VHT
rate with the tx bit rate flags set and this results
in exporting tx bitrate as legacy rate but with HT/VHT
rate flags set, fix this by clearing the tx bitrate
status for each event. This also fixes the below
warning when we do:

iw dev wlan#N station dump

WARNING: net/wireless/util.c:1222 cfg80211

[<c022f104>] (warn_slowpath_null) from [<bf3b9adc>]
(cfg80211_calculate_bitrate+0x110/0x1f4 [cfg80211])
[<bf3b9adc>] (cfg80211_calculate_bitrate [cfg80211]) from
[<bf3dcd54>] (nl80211_put_sta_rate+0x44/0x1dc [cfg80211])
[<bf3dcd54>] (nl80211_put_sta_rate [cfg80211]) from
[<bf3cbc34>] (nl80211_set_interface+0x724/0xd70 [cfg80211])
[<bf3cbc34>] (nl80211_set_interface [cfg80211]) from
[<bf3d0a18>] (nl80211_dump_station+0xdc/0x100 [cfg80211])
[<bf3d0a18>] (nl80211_dump_station [cfg80211])

Fixes: cec17c382140 ("ath10k: add per peer htt tx stats support for 10.4")
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>