wifi: cfg80211: allow only one NAN interface, also in multi radio

wifi: cfg80211: allow only one NAN interface, also in multi radio

According to Wi-Fi Aware (TM) 4.0 specification 2.8, A NAN device can
have one NAN management interface. This applies also to multi radio
devices.
The current code allows a driver to support more than one NAN interface,
if those are not in the same radio.

Fix it.

Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20260107135129.fdaecec0fe8a.I246b5ba6e9da3ec1481ff197e47f6ce0793d7118@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>