Remove stale comments.

(cherry picked from commit 5607da901dcfd962c7dc0fdfd4202ce8dd771131)
Add support for READ DEFECT DATA (10/12) commands.

SPC-4 r2 allows to return empty defect list if the list is not supported.
We don't reallu support defect data lists, but this suppresses some errors.

MFC after:	1 week

(cherry picked from commit 6a41a7221da09c3993ef8e459fc029b326745b99)
Don't confuse frontend with zero length data moves, just return immediately.

MFC after:	1 week

(cherry picked from commit bbcf98d9422d913a50975b33a7a0a9fc9a365db6)
Add LBPERE mode bit definition.

(cherry picked from commit 871e8858c4fb9f60120a48f72920b993155a902f)
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.

(cherry picked from commit eeba2f63ea325ee1c576e00179c55605f6541195)
Remove couple Copan's vendor-specific mode pages.

Those pages are highly system-/hardware-specific, the code is incomplete,
and so they hardly can be useful for anybody else.

(cherry picked from commit 015dd5024297da974865c6c2ad3e854db683f559)