Implement software (mode page) and hardware (config) write protection.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272748 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Fix comment.

MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272749 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f