wifi: ath12k: Fix uninitialized variable access in ath12k_mac_allocate() function

Currently, the uninitialized variable 'ab' is accessed in the
ath12k_mac_allocate() function. Initialize 'ab' with the first radio device
present in the hardware abstraction handle (ah). Additionally, move the
default setting procedure from the pdev mapping iteration to the total
radio calculating iteration for better code readability. Perform the
maximum radio validation check for total_radio to ensure that both num_hw
and radio_per_hw are validated indirectly, as these variables are derived
from total_radio. This also fixes the below Smatch static checker warning.

Smatch warning:
ath12k_mac_allocate() error: uninitialized symbol 'ab'

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1

Fixes: a343d97f ("wifi: ath12k: move struct ath12k_hw from per device to group")
Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Acked-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
Acked-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20250112071630.4059410-5-quic_periyasa@quicinc.com


Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>