wifi: ath12k: add support of station average signal strength

wifi: ath12k: add support of station average signal strength

This adds support for reporting to the kernel the average rssi. This is
done the same way as it was done in ath11k. A simple ewma (with the same
parameters) is updated with each rssi update.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1

Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
Reviewed-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Link: https://patch.msgid.link/20250201211301.357985-1-nico.escande@gmail.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>