mac80211: add vif debugfs driver callbacks

Add debugfs driver callbacks so drivers can add
debugfs entries for interfaces. Note that they
_must_ remove the entries again as add/remove in
the driver doesn't correspond to add/remove in
debugfs; the former is up/down while the latter
is netdev create/destroy.

Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 0a36dc6..deb78e8 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -621,6 +621,8 @@
 				goto err_del_interface;
 		}
 
+		drv_add_interface_debugfs(local, sdata);
+
 		if (sdata->vif.type == NL80211_IFTYPE_AP) {
 			local->fif_pspoll++;
 			local->fif_probe_req++;
@@ -882,6 +884,8 @@
 		 */
 		ieee80211_free_keys(sdata);
 
+		drv_remove_interface_debugfs(local, sdata);
+
 		if (going_down)
 			drv_remove_interface(local, sdata);
 	}