wifi: ath12k: Refactor ath12k_vif structure

wifi: ath12k: Refactor ath12k_vif structure

Move the Data Path (DP)-specific fields from ath12k_vif into a new
structure ath12k_dp_vif, embedded within ath12k_vif. This new structure
contains an array of per-link DP fields represented by ath12k_dp_link_vif.

Since dp_link_vif is small and frequently accessed from ahvif during Tx,
it is stored as an array of structs rather than an array of pointers to
avoid additional indirections and improve cache efficiency. However,
this design comes with a trade-off: because the array is not pointer-based,
it increases memory usage.

Per packet data path makes use of ath12k_dp_vif and ath12k_dp_link_vif.
Add pdev_idx and lmac_id in ath12k_dp_link_vif to avoid accessing ar in
dp tx.

Diagrammatic view of the new structure is below:

+--------------------------------+
| struct ath12k_vif              |
|                                |
|  +--------------------------+  |
|  | struct ath12k_dp_vif     |  |
|  |                          |  |
|  |  +--------------------+  |  |
|  |  | ath12k_dp_link_vif |  |  |
|  |  +--------------------+  |  |
|  |                          |  |
|  |  +--------------------+  |  |
|  |  | ath12k_dp_link_vif |  |  |
|  |  +--------------------+  |  |
|  |                          |  |
|  |  +--------------------+  |  |
|  |  | ath12k_dp_link_vif |  |  |
|  |  +--------------------+  |  |
|  |                          |  |
|  +--------------------------+  |
|                                |
+--------------------------------+

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/20250930131005.2884253-7-quic_rdeuri@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>