Fix a major oversight in r251732 which causes non-VIMAGE kernels to trigger a
KASSERT during TCP hhook registration at boot. Virtualised hook points only
require extra housekeeping and sanity checking when "options VIMAGE" is present.

Reported by:	bdrewery,jh,dhw
Tested by:	dhw
MFC after:	1 week
X-MFC with:	251732