It seems that SAS unlike SPI does not have a dedicated Initiator ID
as all links are peer-to-peer between the initiator and a target
instead of a shared bus.
Previously SAS SIMs had to fake it but now they can completely omit it.
This change was suggested by Jim Harris a long time ago.
I implemented the check as a switch because I suspect that there are
more transports where Initiator ID does not make sense.