wifi: ath11k: don't use static variables in ath11k_debugfs_fw_stats_process()

wifi: ath11k: don't use static variables in ath11k_debugfs_fw_stats_process()

Currently ath11k_debugfs_fw_stats_process() is using static variables to count
firmware stat events. Taking num_vdev as an example, if for whatever reason (
say ar->num_started_vdevs is 0 or firmware bug etc.) the following condition

	(++num_vdev) == total_vdevs_started

is not met, is_end is not set thus num_vdev won't be cleared. Next time when
firmware stats is requested again, even if everything is working fine, we will
fail due to the condition above will never be satisfied.

The same applies to num_bcn as well.

Change to use non-static counters so that we have a chance to clear them each
time firmware stats is requested. Currently only ath11k_fw_stats_request() and
ath11k_debugfs_fw_stats_request() are requesting firmware stats, so clear
counters there.

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

Fixes: da3a9d3c1576 ("ath11k: refactor debugfs code into debugfs.c")
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Acked-by: Kalle Valo <kvalo@kernel.org>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250220082448.31039-3-quic_bqiang@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>