wifi: ath12k: Add support to enable debugfs_htt_stats

Create debugfs_htt_stats file when ath12k debugfs support is enabled.
Add basic ath12k_debugfs_htt_stats_register and handle htt_stats_type
file operations.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Signed-off-by: Dinesh Karthikeyan <quic_dinek@quicinc.com>
Co-developed-by: Ramya Gnanasekar <quic_rgnanase@quicinc.com>
Signed-off-by: Ramya Gnanasekar <quic_rgnanase@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://patch.msgid.link/20240626085854.2500681-2-quic_rgnanase@quicinc.com