wifi: ath12k: Add support for reading variant from ACPI to download board data file

wifi: ath12k: Add support for reading variant from ACPI to download board data file

Currently, ath12k does not support reading variant from ACPI board data
filename extension for downloading board data file.

To address this issue, obtain the string of the ACPI data filename
extension and use it as part of the string to search for the board data
file from board-2.bin.

This patch will not affect QCN9274, because only WCN7850 supports ACPI.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Signed-off-by: Lingbo Kong <quic_lingbok@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://patch.msgid.link/20250113074810.29729-5-quic_lingbok@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>