wifi: ath11k: remove invalid peer create logic

In ath11k_mac_op_assign_vif_chanctx(), there is a logic to
create peer using ar->mac_addr for a STA vdev. This is invalid
because a STA vdev should have a peer created using AP's
MAC address. Besides, if we run into that logic, it means a peer
has already been created earlier, we should not create it again.
So remove it.

This is found during code review.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1
Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.23
Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1
Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1

Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240123025700.2929-2-quic_bqiang@quicinc.com