Fix number of days also added as seconds

I noticed that *n* days would be added as *n* * 86400 + *n* seconds, for example:

```sh
$ ./delay 1d
  1 00:00:01
$ ./delay 2d
  2 00:00:02
$ ./delay 3d
  3 00:00:03
```

It looks like a easy fix, although I am not entirely sure if that fixes all. I just saw `h`, `m`, `s` set `t` variable to 0, so I just copy-and-pasted it and didn't even read the code to know how it's actually done.