wifi: ath12k: defer dp_peer registration when firmware allocates MLD peer ID

wifi: ath12k: defer dp_peer registration when firmware allocates MLD peer ID

For chips with host_alloc_ml_id=true (QCN9274 etc.), the host allocates
the MLD peer ID up front; ath12k_dp_peer_create() publishes the dp_peer
into dp_hw->dp_peers[] using that ID immediately. WCN7850/QCC2072 does
not work that way: the firmware picks the ID and only tells the host
afterwards via HTT_T2H_MSG_TYPE_MLO_RX_PEER_MAP, so the publication has
to be delayed until the event arrives.

Introduce ATH12K_MLO_PEER_ID_PENDING (0xFFFE) as a sentinel for "is_mlo,
but ID not yet known". On the firmware-allocates path:

  - ath12k_mac_op_sta_state(NOTEXIST->NONE) skips ath12k_peer_ml_alloc()
    and stores PENDING in ahsta->ml_peer_id and dp_params.peer_id;
  - ath12k_dp_peer_create() skips dp_peer registration until a real ID is
    known;
  - ath12k_peer_create() leaves peer->ml_id at INVALID so consumer sites
    do not treat PENDING as a real ID;
  - ath12k_peer_ml_free() and ath12k_mac_dp_peer_cleanup() skip the
    dp_peers[] write and the free_ml_peer_id_map clear when
    host_alloc_ml_id is false or the ID is still PENDING.

The HTT handler change that resolves the PENDING ID is added in a
follow-up patch.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.115823.3

Signed-off-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com>
Reviewed-by: Rameshkumar Sundaram <rameshkumar.sundaram@oss.qualcomm.com>
Link: https://patch.msgid.link/20260720-ath12k-fw-allocated-ml-peer-id-v2-7-630632758a80@oss.qualcomm.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>