wifi: ath12k: Resolve ping failure from AP to Station

Currently, the key_cipher (a member of the ath12k_vif structure)
is populated when the link address matches the ieee80211_vif address
inside ath12k_install_key().

However, in MLD AP, the link address and vif address can differ,
resulting in key_cipher not being populated, which causes multicast
packet failures.

This fix addresses the issue by setting the key_cipher to be
link-specific.

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

Co-developed-by: Yuvarani V <quic_yuvarani@quicinc.com>
Signed-off-by: Yuvarani V <quic_yuvarani@quicinc.com>
Signed-off-by: Aaradhana Sahu <quic_aarasahu@quicinc.com>
Signed-off-by: Raj Kumar Bhagat <quic_rajkbhag@quicinc.com>
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>