f2fs: format segment_info's show for better legibility

The original segment_info's show is a bit out-of-format:

[root@guz Demoes]# cat /proc/fs/f2fs/loop0/segment_info
0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
......
0 0 0 0 0 0 0 0 0 0
0 0 1 0 0 1 [root@guz Demoes]#

so we fix it here for better legibility.
[root@guz Demoes]# cat /proc/fs/f2fs/loop0/segment_info
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
......
0 0 0 0 0 0 0 0 0 0
0 0 1 0 0 1
[root@guz Demoes]#

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>