Add KASSERTs to catch the case where a developer may have forgotten to
set bo_bsize on a bufobj.

This is a slight modification of the patch provided.

PR:		193146
Submitted by:	Conrad Meyer <conrad.meyer@isilon.com>
Sponsored by:	EMC Isilon Storage Division


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271070 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f