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>