wifi: ath12k: Move HTT Tx specific code to newly introduced files

wifi: ath12k: Move HTT Tx specific code to newly introduced files

WLAN Host driver interacts with the Firmware and vice versa using
Host-To-Target (HTT) interface.

Relocate HTT specific code from dp_tx.c to dp_htt.c introduced for
HTT interface. These code is compiled as part of the common module
ath12k.ko.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-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: Harsh Kumar Bijlani <quic_hbijlani@quicinc.com>
Signed-off-by: Ripan Deuri <quic_rdeuri@quicinc.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Reviewed-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com>
Link: https://patch.msgid.link/20250828173553.3341351-20-quic_rdeuri@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>