wifi: ath9k: fix possible integer overflow in ath9k_get_et_stats()

wifi: ath9k: fix possible integer overflow in ath9k_get_et_stats()

[ Upstream commit 3f66f26703093886db81f0610b97a6794511917c ]

In 'ath9k_get_et_stats()', promote TX stats counters to 'u64'
to avoid possible integer overflow. Compile tested only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Dmitry Kandybka <d.kandybka@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://patch.msgid.link/20240725111743.14422-1-d.kandybka@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>