dump.f2fs: print more info

dump.f2fs shows more info:
 * nat entry version
 * sit entry mtime

Signed-off-by: Sheng Yong <shengyong1@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>