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>

fs/hugetlbfs/inode.c

@@ -970,7 +970,7 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
 
 	d_instantiate(path.dentry, inode);
 	inode->i_size = size;
-	inode->i_nlink = 0;
+	clear_nlink(inode);
 
 	error = -ENFILE;
 	file = alloc_file(&path, FMODE_WRITE | FMODE_READ,