mac80211: remove sta_info debugfs sub-struct

Since the previous patch, the struct only has a single member,
so remove the struct and leave just the single member.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/rate.h b/net/mac80211/rate.h
index 624fe5b..8d32607 100644
--- a/net/mac80211/rate.h
+++ b/net/mac80211/rate.h
@@ -96,9 +96,9 @@
 {
 #ifdef CONFIG_MAC80211_DEBUGFS
 	struct rate_control_ref *ref = sta->rate_ctrl;
-	if (ref && sta->debugfs.dir && ref->ops->add_sta_debugfs)
+	if (ref && sta->debugfs_dir && ref->ops->add_sta_debugfs)
 		ref->ops->add_sta_debugfs(ref->priv, sta->rate_ctrl_priv,
-					  sta->debugfs.dir);
+					  sta->debugfs_dir);
 #endif
 }