Remove the freelist member from vm_physseg

The new world order of pmemrange makes this data completely redundant
(being dealt with by the pmemrange constraints instead). Remove all code
that messes with the freelist.

While touching every caller of uvm_page_physload() anyway, add the flags
argument to all callers (all but one is 0 and that one already used
PHYSLOAD_DEVICE) and remove the macro magic to allow callers to continue
without it.

Should shrink the code a bit, as well.

matthew@ pointed out some mistakes i'd made.
``freelist death, I like. Ok.' ariane@
`I agree with the general direction, go ahead and i'll fix any fallout
shortly'' miod@ (68k 88k and vax i could not check would build)

Normalize sentinel. Use _MACHINE_*_H_ and _<ARCH>_*_H_ properly and consitently.

Discussed and okay drahn@. Okay deraadt@.

Fix KERNBASE, so that profiling kernels initialize (but profiling is broken
at the moment).

branches: 1.1.1;
Initial revision