wifi: ath12k: fix read pointer after free in ath12k_mac_assign_vif_to_vdev()

In the Linux kernel, the following vulnerability has been resolved: wifi: ath12k: fix read pointer after free in ath12k_mac_assign_vif_to_vdev() In ath12k_mac_assign_vif_to_vdev(), if arvif is created on a different radio, it gets deleted from that radio through a call to ath12k_mac_unassign_link_vif(). This action frees the arvif pointer. Subsequently, there is a check involving arvif, which will result in a read-after-free scenario. Fix this by moving this check after arvif is again assigned via call to ath12k_mac_assign_link_vif(). Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1