nilfs2: remove unlikely directive causing mis-conversion of error code

The following error code handling in nilfs_segctor_write() function
wrongly converted negative error codes to a truth value (i.e. 1):

   err = unlikely(err) ? : res;

which originaly meant to be

   err = err ? : res;

This mis-conversion caused that write or sync functions receive the
unexpected error code.  This fixes the bug by removing the unlikely
directive.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: stable@kernel.org

fs/nilfs2/segment.c

@@ -1829,8 +1829,8 @@ static int nilfs_segctor_write(struct nilfs_sc_info *sci,
 		err = nilfs_segbuf_write(segbuf, &wi);
 
 		res = nilfs_segbuf_wait(segbuf, &wi);
-		err = unlikely(err) ? : res;
-		if (unlikely(err))
+		err = err ? : res;
+		if (err)
 			return err;
 	}
 	return 0;