wifi: ath12k: don't put ieee80211_chanctx_conf struct in ath12k_link_vif

wifi: ath12k: don't put ieee80211_chanctx_conf struct in ath12k_link_vif

ieee80211_chanctx_conf struct is not put at the end of ath12k_link_vif.
Note ieee80211_chanctx_conf has flexible array member inside it, causing
below warning with GCC-14:

drivers/net/wireless/ath/ath12k/core.h:298:39: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Although there is no issue for now since the array is not getting used,
this should be fixed to avoid any potential data corruption issue in the
future.

Remove this struct from ath12k_link_vif, fetch it from ieee80211_bss_conf
instead when needed.

This change only applies to WCN7850, and should has no impact on other
chipsets.

This is an alternative to the solution proposed in [1].

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

Reported-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Closes: https://msgid.link/Z8-Snz86Xfwdlyd7@kspp # [1]
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250321-ath12k-dont-put-chanctx-in-arvif-v1-1-c8e93061952b@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>