For CPUs which do hardware cache line unaliasing, use direct map to
access sfbufs.

Suggested and reviewed by:	alc
Tested by:	Michael Moll <kvedulv@kvedulv.de>
Sponsored by:	The FreeBSD Foundation


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270429 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f