Add deprecation notice to vpo.4 / Remove vpo.4

[imp]

Summary

This driver has seen no real changes for almost 20 years. It's for
hardware that's 25 years old. It has no reports of active use, nor
has it been seen in the NYCBug dmesg database at all. Schedule
its removal for 13.0.

Relnote: Yes
MFC After: 3 days

Remove vpo.4

The Parallel Port SCSI adapter was interesting for 100MB ZIP drives, but is no
longer used or maintained. Remove it from the tree.

The Parallel Port microsequencer (microseq.9) is now mostly unused in the tree,
but remains. PPI still refrences it, but doesn't use its full functionality.

Relnotes: Yes
Discussed on: arch@

[ihor_antonovs.family]

I am just a humble FreeBSD user, but I think this absolutely must be done.
Reducing code footprint, attack surface and cognitive overhead for those who maintain the code.
+1

[rgrimes]

Please create a review to first add deprecation notices to the man pages and a gone_in to the driver, with a RELNOTES: y, and a MFC 11+12. Then this can be committed with a MFC: never right behind it.

[imp]

In D23389#513038, @rgrimes wrote:

Please create a review to first add deprecation notices to the man pages and a gone_in to the driver, with a RELNOTES: y, and a MFC 11+12. Then this can be committed with a MFC: never right behind it.

No. That's in this review. It is a separate commit already.

[imp]

Ooops. I see that phab isn't smart enough to allow multiple changes to be posted in one review when a later change removes the file :(
https://reviews.freebsd.org/D23403
has the review for the deprecation notice that I already have in my tree.

[imp]

I have a memory of Rod suggesting that I also add gone_in() which I've done before the commit. Can't find where he made that suggestion though, but it was a good idea.