Add proper disable/enable hooks to the default scripts so that this is only
run when asked for by the user.  Right now, hv_kvpd is run on every boot.

Don't do that.

Add hv_kvpd_enable= for this script to be run.

MFC with 271493

MFC after:	2 weeks
Relnotes:	yes


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271688 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f