wifi: ath12k: fix documentation on firmware stats

Regarding the firmware stats events handling, the comment in
ath12k_mac_get_fw_stats() says host determines whether all events have been
received based on 'end' tag in TLV. This is wrong as there is no such tag
at all, actually host makes the decision totally by itself based on the
stats type and active pdev/vdev counts etc.

Fix it to correctly reflect the logic.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00284.1-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
Tested-on: QCN9274 hw2.0 WLAN.WBE.1.5-01651-QCAHKSWPL_SILICONZ-1

Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Link: https://patch.msgid.link/20250612-ath12k-fw-fixes-v1-1-12f594f3b857@quicinc.com


Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>