wifi: ath12k: Fetch regdb.bin file from board-2.bin

wifi: ath12k: Fetch regdb.bin file from board-2.bin

Currently, ath12k_core_fetch_regdb() finds regdb.bin file through
board id's but in board-2.bin file regdb.bin file is present with
default board id because of which regdb.bin is not fetched.

Add support to fetch regdb.bin file from board-2.bin through
default board id.

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

Signed-off-by: Aaradhana Sahu <quic_aarasahu@quicinc.com>
Reviewed-by: Aditya Kumar Singh <quic_adisi@quicinc.com>
Link: https://patch.msgid.link/20250116032835.118397-1-quic_aarasahu@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>