wifi: ath12k: use kfree_skb() instead of kfree()

Sk_buffs are supposed to be freed with kfree_skb().

Fixes: d8899132 ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/Y+4ejiYakhEvEw7c@kili