wifi: ath12k: remove unused ATH12K_BD_IE_BOARD_EXT

Currently ATH12K_BD_IE_BOARD_EXT is not used, so remove it.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20231216060140.30611-4-quic_bqiang@quicinc.com

drivers/net/wireless/ath/ath12k/hw.h

@@ -245,7 +245,6 @@ enum ath12k_bd_ie_board_type {
 enum ath12k_bd_ie_type {
 	/* contains sub IEs of enum ath12k_bd_ie_board_type */
 	ATH12K_BD_IE_BOARD = 0,
-	ATH12K_BD_IE_BOARD_EXT = 1,
 };
 
 struct ath12k_hw_regs {