nilfs2: use list_first_entry

This uses list_first_entry macro instead of list_entry if it's used to
get the first entry.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/recovery.c b/fs/nilfs2/recovery.c
index ba4a645..a604ac0 100644
--- a/fs/nilfs2/recovery.c
+++ b/fs/nilfs2/recovery.c
@@ -387,9 +387,9 @@
 static void dispose_recovery_list(struct list_head *head)
 {
 	while (!list_empty(head)) {
-		struct nilfs_recovery_block *rb
-			= list_entry(head->next,
-				     struct nilfs_recovery_block, list);
+		struct nilfs_recovery_block *rb;
+
+		rb = list_first_entry(head, struct nilfs_recovery_block, list);
 		list_del(&rb->list);
 		kfree(rb);
 	}
@@ -416,9 +416,9 @@
 void nilfs_dispose_segment_list(struct list_head *head)
 {
 	while (!list_empty(head)) {
-		struct nilfs_segment_entry *ent
-			= list_entry(head->next,
-				     struct nilfs_segment_entry, list);
+		struct nilfs_segment_entry *ent;
+
+		ent = list_first_entry(head, struct nilfs_segment_entry, list);
 		list_del(&ent->list);
 		kfree(ent);
 	}