More CARP issues under 12

[Pete French]

So, another datapoint on this - I just PXE booted the 12.0-RELEASE image
downloaded from https://mfsbsd.vx.sk/ and that works fine. Which means
that it siether something which has crept in since 12.0-RELEASE or its
something to do with my config on that machine.

I did try and buld an mfsroot image of the kernel I am trying to
deploy,. but that failed, which is a bit of a shame, as thats easier to
try than the full upgrade (because rolling that back after a crash
is tricky!). The laternative is to bild 12.0-RELEASE and see if that boots
up. Not sure when I will get around to trying either of those though.

-pete.