nit in sysinstall menu

[Ben Kaduk]

[remove ``phosphor'' from ``phosphor burn-in'' in sysinstall]
On 6/29/07, Doug Barton <dougb at freebsd.org> wrote:
> This is a good sort of thing to submit in a PR so that it doesn't get
> lost.
>
> Thanks,
>
> Doug
>
> --
>
>     This .signature sanitized for your protection
>

Okay; I'll be submitting a lot of PR's in the next couple of days,
then, mostly for small changes like this.

-Ben Kaduk