Some groundwork for later Informational Exceptions support.

This includes support for:
 - Read-Write Error Recovery mode page;
 - Informational Exceptions Control mode page;
 - Logical Block Provisioning mode page;
 - LOG SENSE command.

No real Informational Exceptions features yet. This is only a placeholder.

Sponsored by:	iXsystems, Inc.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273073 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f