wifi: ath11k: move some firmware stats related functions outside of debugfs

wifi: ath11k: move some firmware stats related functions outside of debugfs

Commit b488c766442f ("ath11k: report rssi of each chain to mac80211 for QCA6390/WCN6855")
and commit c3b39553fc77 ("ath11k: add signal report to mac80211 for QCA6390 and WCN6855")
call debugfs functions in mac ops. Those functions are no-ops if CONFIG_ATH11K_DEBUGFS is
not enabled, thus cause wrong status reported.

Move them to mac.c.

Besides, since WMI_REQUEST_RSSI_PER_CHAIN_STAT and WMI_REQUEST_VDEV_STAT stats could also
be requested via mac ops, process them directly in ath11k_update_stats_event().

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.37

Fixes: b488c766442f ("ath11k: report rssi of each chain to mac80211 for QCA6390/WCN6855")
Fixes: c3b39553fc77 ("ath11k: add signal report to mac80211 for QCA6390 and WCN6855")
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250220082448.31039-5-quic_bqiang@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>