path_id: rework SAS device handling

path_id: rework SAS device handling

Lun numbers < 256 are displayed as "lun-x".  Lun numbers >= 256 use
the lun number format previously used in fibre channel by-path
links, 0xabcd012300000000. This lun numbering scheme is implemented
for sas, fibre channel, iscsi.

I want it to be clearly understood that this patch changes the
/dev/disk/by-path names for fc devices.  Here is an example of the
change:
  Old: pci-0000:0c:00.1-fc-0x204700a0b81130aa:0x00fa000000000000
  New: pci-0000:0c:00.1-fc-0x204700a0b81130aa-lun-250