wifi: ath11k: Consistently use ath11k_vif_to_arvif()

Helper function ath11k_vif_to_arvif() exists to retrieve a struct
ath11k_vif from a struct ieee80211_vif. However, in multiple places
this logic is open-coded with inline typecasting. Since the
typecasting prevents the compiler from type-checking the source and
destination, update the driver to consistently use the helper
function.

No functional changes, compile tested only.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230821-ath11k_vif_to_arvif-v1-1-fa2c3b60b5cf@quicinc.com

drivers/net/wireless/ath/ath11k/testmode.c

@@ -350,7 +350,7 @@ static int ath11k_tm_cmd_wmi(struct ath11k *ar, struct nlattr *tb[],
 	if (ar->ab->fw_mode != ATH11K_FIRMWARE_MODE_FTM &&
 	    (tag == WMI_TAG_VDEV_SET_PARAM_CMD || tag == WMI_TAG_UNIT_TEST_CMD)) {
 		if (vif) {
-			arvif = (struct ath11k_vif *)vif->drv_priv;
+			arvif = ath11k_vif_to_arvif(vif);
 			*ptr = arvif->vdev_id;
 		} else {
 			ret = -EINVAL;