wifi: mac80211: Fix sparse warning for monitor_sdata

Use rcu_access_pointer() to avoid sparse warning in
drv_remove_interface().

Signed-off-by: Alexander Wetzel <Alexander@wetzel-home.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202502130534.bVrZZBK0-lkp@intel.com/
Fixes: 646262c ("wifi: mac80211: remove debugfs dir for virtual monitor")
Link: https://patch.msgid.link/20250213214330.6113-1-Alexander@wetzel-home.de
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: alexw65500

net/mac80211/driver-ops.c

@@ -121,7 +121,7 @@ void drv_remove_interface(struct ieee80211_local *local,
 	 * The virtual monitor interface doesn't get a debugfs
 	 * entry, so it's exempt here.
 	 */
-	if (sdata != local->monitor_sdata)
+	if (sdata != rcu_access_pointer(local->monitor_sdata))
 		ieee80211_debugfs_recreate_netdev(sdata,
 						  sdata->vif.valid_links);