[SCSI] make some sas class properties optional

aic94xx doesn't have a use for the bay or enclosure identifiers.
Also, I think it's not going to need a get_linkerrors(), so wire up
all of these exported properties as conditional on the underlying
function support.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
1 file changed