svn revisions r269964 and r269963 seemed to have impaired small memory
footprint systems(32M/64M) and didn't leave enough free memory to load modules
when it was setting up page tables that for sizes that are never used on
these smallish boards.

Set kmem_zmax to PAGE_SIZE on these smaller systems (< 128M) to keep this
from happening. Verified on mips32 h/w.

PR:             193465
Submitted by:   delphij
Reviewed by:    adrian


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271944 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f