force the pool of pmapvp onto PAGE_SIZE allocations by specifying a

force the pool of pmapvp onto PAGE_SIZE allocations by specifying a
pool allocator. pmapvp is 1024 bytes, and the size * 8 change in pools
without an allocator being specified tries to place it on large pages.
you need pmap to use large pages, and pmap isnt set up yet.

fixed a very early fault on macppc.
debugged with and tested by krw@
ok deraadt@ krw@