wifi: ath12k: use arvif instead of link_conf in ath12k_mac_set_key()

wifi: ath12k: use arvif instead of link_conf in ath12k_mac_set_key()

Currently, in ath12k_mac_set_key(), if sta is not present, the address is
retrieved from link_conf's bssid or addr member, depending on the interface
type.

When operating as an ML station and during shutdown, link_conf will not be
available. This can result in the following error:

ath12k_pci 0004:01:00.0: unable to access bss link conf in set key for vif AA:BB:CC:DD:EE:FF link 1

The primary purpose of accessing link_conf is to obtain the address for
finding the peer. However, since arvif is always valid in this call, it can
be used instead.

Add change to use arvif instead of link_conf.

A subsequent change will expose this issue but since tear down will give
error, this is included first.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1
Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00130-QCAHKSWPL_SILICONZ-1.97421.5 # Nicolas Escande

Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Tested-by: Nicolas Escande <nico.escande@gmail.com>
Link: https://patch.msgid.link/20250204-unlink_link_arvif_from_chanctx-v2-5-764fb5973c1a@oss.qualcomm.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>