Bluetooth: Mesh: Fix clearing Friend state upon reset

Not clearing the Friend state could risk invalid timers staying
active, etc.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

subsys/bluetooth/host/mesh/main.c

@@ -120,6 +120,10 @@ void bt_mesh_reset(void)
 		bt_mesh_lpn_disable(true);
 	}
 
+	if (IS_ENABLED(CONFIG_BT_MESH_FRIEND)) {
+		bt_mesh_friend_clear_net_idx(BT_MESH_KEY_ANY);
+	}
+
 	if (IS_ENABLED(CONFIG_BT_MESH_GATT_PROXY)) {
 		bt_mesh_proxy_gatt_disable();
 	}