nilfs2: An unassigned variable is assigned to a never used structure member

nilfs2: In procedure 'nilfs_get_sb()', when a nilfs filesysttem is
mounted for the first time, local variable 'nilfs->ns_last_cno' is
used before loading the latest checkpoint number from disk (in
'nilfs_fill_super'). 'nilfs->ns_last_cno' is assigned to 'sd.cno', but
'sd.cno' has never been used in the procedure.
Signed-off-by: NZhang Qiang <zhangqiang.buaa@gmail.com>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/super.c

@@ -1103,10 +1103,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
 	 */
 	sd.sbi = nilfs_find_sbinfo(nilfs, !(flags & MS_RDONLY), sd.cno);
 
-	if (!sd.cno)
-		/* trying to get the latest checkpoint.  */
-		sd.cno = nilfs_last_cno(nilfs);
-
 	/*
 	 * Get super block instance holding the nilfs_sb_info struct.
 	 * A new instance is allocated if no existing mount is present or