Use the correct macro for listing the maximum bus space size.

Without this, it fails to compile on i386 PAE builds.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275870 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Update the use of bus space macros to be more correct.

This was a problem on i386 PAE builds.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275871 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f