ath10k: Remove unneeded locks during HTT RX attach

Fix two issues:

* Bail out properly when RX buffer allocation fails at init time.
* Do not acquire the rx ring lock during attach() since we
  don't rearm the replenish timer.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: Fix TXOP handling

The channel time duration programmed in the HW is in absolute microseconds,
while mac80211 gives the txop in units of 32 microseconds. Handle this
properly.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: unify header inclusion guard names

Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>