[SCSI] scsi_transport_sas.c: display port identifier

This patch displays the port identifier on
the folder attribute; located in the middle digit.

/sys/class/sas_rphy/rphy-%x:%x:%x

The port identifier is basically the unique identifier
for each sas domain.

Signed-off-by: Eric Moore <Eric.Moore@lsil.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>