wifi: ath12k: handle scan link during vdev create

wifi: ath12k: handle scan link during vdev create

For scanning purposes, the driver can use link ID 15 (scan link). A future
change will make non-ML interfaces to select the scan link. In this
scenario, arvif->link_id will be used to retrieve the link configuration in
ath12k_mac_vdev_create(). However, link ID 15 is not recognized as a valid
link ID in the upper kernel, which will result in a failure to fetch
link_conf and subsequently cause the scan to fail.

To avoid this issue, ensure link_conf is fetched only when the link ID is
within the valid range. Since link_conf cannot be retrieved using the scan
link, use vif->addr as the Ethernet address for creating the scan vdev.
This address will serve as the source address (address 2) in the probe
request frames during scanning. Additionally, use the automatic Tx power
value for the vdev. As this is a scan vdev, these values do not affect the
scan functionality.

Note that vif->addr will only be taken when a valid link_conf can not be
fetched. Otherwise, link_conf's address will be taken as address 2.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1

Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Link: https://patch.msgid.link/20250417-fix_scan_vdev_handling-v3-1-9ec42513d26b@oss.qualcomm.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>