emulators/virtualbox-ose: Remove unnecessary dependency on 32-bit compat for amd64

[vvd]

Summary

Details are here: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=266382

Tested build in poudriere: 12.4, 13.1, 13.2 amd64.

[arrowd]

Did you conduct run-testing for this change?

[olce]

I've been using this change since at least start of May 2022, so for more than one year, on about 5 points of 13-STABLE, including a very recent one, and with lots of virtual machines.