wifi: ath12k: Avoid packet offset and FCS length from Rx TLV

wifi: ath12k: Avoid packet offset and FCS length from Rx TLV

Currently, the packet offset and FCS length are fetched from the MSDU Rx
TLV data, a logic inherited from ath11k. However, for ath12k 802.11be
hardware, the Rx TLV will not be present in the MSDU data. Instead, this
information is constant. Therefore, remove the existing FCS trim and the
packet offset fetch code. Handle the packet offset with the constant in
the merge MSDU procedure.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-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: P Praneesh <quic_ppranees@quicinc.com>
Tested-by: Nicolas Escande <nico.escande@gmail.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Link: https://patch.msgid.link/20250324062518.2752822-7-quic_periyasa@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>