wifi: brcmfmac: don't allow arp/nd offload to be enabled if ap mode exists

wifi: brcmfmac: don't allow arp/nd offload to be enabled if ap mode exists

Add a check to determine whether arp/nd offload enabling
request is allowed. If there is any interface acts as ap
mode and is operating, reject the request of arp offload
enabling from cfg80211.

Signed-off-by: Ting-Ying Li <tingying.li@cypress.com>
Signed-off-by: Ian Lin <ian.lin@infineon.com>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Link: https://patch.msgid.link/20250606093444.15753-1-ian.lin@infineon.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>