wifi: ath12k: ath12k_start_vdev_delay(): convert to use ar

To support single wiphy abstraction, remove the mac80211 hw data
dependency from the start vdev delay function. This way, this
function can be extended to handle multiple link/radio in the future.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240103063731.3356060-11-quic_periyasa@quicinc.com