ath11k: Don't cast ath11k_skb_cb to ieee80211_tx_info.control

ath11k: Don't cast ath11k_skb_cb to ieee80211_tx_info.control

The driver_data area of ieee80211_tx_info is used in ath11k for
ath11k_skb_cb. The first function in the TX patch which rewrites it to
ath11k_skb_cb is already ath11k_mac_op_tx. No one else in the code path
must use it for something else before it reinitializes it. Otherwise the
data has to be considered uninitialized or corrupt.

But the ieee80211_tx_info.control shares exactly the same area as
ieee80211_tx_info.driver_data and ath11k is still using it. This results in
best case in a

  ath11k c000000.wifi1: no vif found for mgmt frame, flags 0x0

or (slightly worse) in a kernel oops.

Instead, the interesting data must be moved first into the ath11k_skb_cb
and ieee80211_tx_info.control must then not be used anymore.

Tested-on: IPQ8074 hw2.0 WLAN.HK.2.4.0.1.r1-00026-QCAHKSWPL_SILICONZ-2

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201119154235.263250-1-sven@narfation.org