RDMA/rtrs-srv: Fix several issues in rtrs_srv_destroy_path_files

There are several issues in the function which is supposed to be paired
with rtrs_srv_create_path_files.

1. rtrs_srv_stats_attr_group is not removed though it is created in
   rtrs_srv_create_stats_files.

2. it makes more sense to check kobj_stats.state_in_sysfs before destroy
   kobj_stats instead of rely on kobj.state_in_sysfs.

3. kobject_init_and_add is used for both kobjs (srv_path->kobj and
   srv_path->stats->kobj_stats), however we missed to call kobject_del
   for srv_path->kobj which was called in free_path.

4. rtrs_srv_destroy_once_sysfs_root_folders is independent of either
   kobj or kobj_stats.
Acked-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Link: https://lore.kernel.org/r/20221117101945.6317-8-guoqing.jiang@linux.devSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/ulp/rtrs/rtrs-srv-sysfs.c

@@ -304,12 +304,18 @@ int rtrs_srv_create_path_files(struct rtrs_srv_path *srv_path)
 
 void rtrs_srv_destroy_path_files(struct rtrs_srv_path *srv_path)
 {
-	if (srv_path->kobj.state_in_sysfs) {
+	if (srv_path->stats->kobj_stats.state_in_sysfs) {
+		sysfs_remove_group(&srv_path->stats->kobj_stats,
+				   &rtrs_srv_stats_attr_group);
 		kobject_del(&srv_path->stats->kobj_stats);
 		kobject_put(&srv_path->stats->kobj_stats);
+	}
+
+	if (srv_path->kobj.state_in_sysfs) {
 		sysfs_remove_group(&srv_path->kobj, &rtrs_srv_path_attr_group);
+		kobject_del(&srv_path->kobj);
 		kobject_put(&srv_path->kobj);
-
-		rtrs_srv_destroy_once_sysfs_root_folders(srv_path);
 	}
+
+	rtrs_srv_destroy_once_sysfs_root_folders(srv_path);
 }