mac80211: stop plink timer only on mesh interfaces

Since mesh_plink_quiesce() would unconditionally delete
the plink timer, and the timer initialization was recently
moved into the mesh code path, suspending with a non-mesh
interface now causes a crash. Fix this by only deleting
the plink timer for mesh interfaces.

Reported-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Tested-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mesh_plink.c

@@ -592,6 +592,9 @@ static void mesh_plink_timer(unsigned long data)
 #ifdef CONFIG_PM
 void mesh_plink_quiesce(struct sta_info *sta)
 {
+	if (!ieee80211_vif_is_mesh(&sta->sdata->vif))
+		return;
+
 	if (del_timer_sync(&sta->plink_timer))
 		sta->plink_timer_was_running = true;
 }