filesystems: add missing nlink wrappers

Replace direct i_nlink updates with the respective updater function
(inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count).

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/hfs/dir.c b/fs/hfs/dir.c
index b4d70b1..bce4eef 100644
--- a/fs/hfs/dir.c
+++ b/fs/hfs/dir.c
@@ -198,7 +198,7 @@
 
 	res = hfs_cat_create(inode->i_ino, dir, &dentry->d_name, inode);
 	if (res) {
-		inode->i_nlink = 0;
+		clear_nlink(inode);
 		hfs_delete_inode(inode);
 		iput(inode);
 		return res;
@@ -227,7 +227,7 @@
 
 	res = hfs_cat_create(inode->i_ino, dir, &dentry->d_name, inode);
 	if (res) {
-		inode->i_nlink = 0;
+		clear_nlink(inode);
 		hfs_delete_inode(inode);
 		iput(inode);
 		return res;