ath10k: fix PMF by using AES-CMAC/IGTK software crypto

While testing with older supplicant, .drv_set_key() was failing due to
higher than ath10k firmware could handle key_index (WMI_MAX_KEY_INDEX == 3).

--
wpa_driver_nl80211_set_key: ifindex=15 alg=4 addr=0x7f02b129fbe3 key_idx=4 set_tx=0 seq_len=6 key_len=16
    broadcast key
nl80211: set_key failed; err=-22 Invalid argument)
wlan0: WPA: Failed to configure IGTK to the driver
wlan0: RSN: Failed to configure IGTK
--

In order to fix this case (PMF: AES-CMAC/IGTK) force the AES_CMAC cipher to
be handled by software.
Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/mac.c

@@ -66,8 +66,8 @@ static int ath10k_send_key(struct ath10k_vif *arvif,
 		arg.key_cipher = WMI_CIPHER_WEP;
 		break;
 	case WLAN_CIPHER_SUITE_AES_CMAC:
-		/* this one needs to be done in software */
-		return 1;
+		WARN_ON(1);
+		return -EINVAL;
 	default:
 		ath10k_warn(ar, "cipher %d is not supported\n", key->cipher);
 		return -EOPNOTSUPP;
@@ -4070,6 +4070,10 @@ static int ath10k_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	int ret = 0;
 	u32 flags = 0;
 
+	/* this one needs to be done in software */
+	if (key->cipher == WLAN_CIPHER_SUITE_AES_CMAC)
+		return 1;
+
 	if (key->keyidx > WMI_MAX_KEY_INDEX)
 		return -ENOSPC;