nilfs2: remove meaningless EBUSY case from nilfs_get_sb function

The following EBUSY case in nilfs_get_sb() is meaningless.  Indeed,
this error code is never returned to the caller.

    if (!s->s_root) {
          ...
    } else if (!(s->s_flags & MS_RDONLY)) {
        err = -EBUSY;
    }

This simply removes the else case.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/nilfs2/super.c

@@ -1186,8 +1186,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
 
 		s->s_flags |= MS_ACTIVE;
 		need_to_close = 0;
-	} else if (!(s->s_flags & MS_RDONLY)) {
-		err = -EBUSY;
 	}
 
 	up(&sd.bdev->bd_mount_sem);