wifi: ath12k: Fix a NULL pointer dereference in ath12k_mac_op_hw_scan()

wifi: ath12k: Fix a NULL pointer dereference in ath12k_mac_op_hw_scan()

In ath12k_mac_op_hw_scan(), the return value of kzalloc() is directly
used in memcpy(), which may lead to a NULL pointer dereference on
failure of kzalloc().

Fix this bug by adding a check of arg.extraie.ptr.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4

Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230726092625.3350-1-quic_wgong@quicinc.com