wifi: ath12k: refactor ath12k_mac_allocate() and ath12k_mac_destroy()

wifi: ath12k: refactor ath12k_mac_allocate() and ath12k_mac_destroy()

Currently, the MAC allocation and destroy helper functions are tightly
coupled with the link/radio (ar) structure. In the future, to support
single/Multi link operations, need to refactor these helper functions
across the core and mac sub modules, so that it can be easy to scale
these functions to support single/Multi link operations.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20231206034920.1037449-3-quic_periyasa@quicinc.com