jffs2: fix searching for latest version in jffs2_1pass_list_inodes()

We need to update i_version inside cycle to find really latest version
inside jffs2_1pass_list_inodes(). With that fixed we can use isize inside
dump_inode() instead of calling expensive jffs2_1pass_read_inode().

Signed-off-by: Alexey Neyman <avn@emcraft.com>
Signed-off-by: Ilya Yanok <yanok@emcraft.com>