ext4: fix incorrect offset

The last argument of ext4_check_dir_entry is dentry offset int the
file.  Luckily this error only results in the wrong offset being
printed in the eventual error message.

Signed-off-by: Wang Jianjian <wangjianjian0@foxmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/tencent_F992989953734FD5DE3F88ECB2191A856206@qq.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>