fs/dlm: use list_add_tail() instead of open-coding list insertion

Replace the manual list pointer manipulation in add_ordered_member()
with the standard list_add_tail() helper. The original code explicitly
updated ->prev and ->next pointers to insert @NewLIST before @tmp,
which is exactly what list_add_tail(newlist, tmp) provides.

Using the list macro improves readability, removes a source of
potential pointer bugs, and satisfies the existing FIXME requesting
conversion to the list helpers. No functional change in the ordering
logic for DLM members.

Signed-off-by: Shaurya Rane <ssrane_b23@ee.vjti.ac.in>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

Author: shauryarane05

fs/dlm/member.c

@@ -299,11 +299,7 @@ static void add_ordered_member(struct dlm_ls *ls, struct dlm_member *new)
 	if (!memb)
 		list_add_tail(newlist, head);
 	else {
-		/* FIXME: can use list macro here */
-		newlist->prev = tmp->prev;
-		newlist->next = tmp;
-		tmp->prev->next = newlist;
-		tmp->prev = newlist;
+		list_add_tail(newlist, tmp);
 	}
 }