wifi: ath12k: add ath12k_ab_to_ah() and ath12k_ab_set_ah()

Currently, one or more ath12k_hw is part of a device (struct ath12k_base) but
in future, it would be part of device group abstraction (struct
ath12k_hw_group), i.e., when multiple radios (ar) across different devices can
be combined together in a device group (struct ath12k_hw_group).

In order to facilitate the above transition, introduce helpers
ath12k_ab_to_ah() and ath12k_ab_set_ah() to get and set values of ath12k_hw
respectively.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-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: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Signed-off-by: Harshitha Prem <quic_hprem@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://patch.msgid.link/20241128165026.2618331-3-kvalo@kernel.org