devd: remove the scsi regexp

We don't really use the scsi regexp for anything. The rescan was a
workaround that was fixed a long time ago and has been disabled for
ages. And the regexp was incomplete.

Approved by: re@ (gjb)
Sponsored by: Netflix

(cherry picked from commit 926e825ef823f49e371f61780634475a1f19c812)
(cherry picked from commit cb95daaa91895a74a2f6d2db0d0773517a34ab99)