[SCSI] mptsas: fix phy identifiers

This patch from Eric fixes handling of the phy identifiers in mptsas.
I've split it up from his bigger patch as it should go into 2.6.14
still.

Signed-off-by: Eric Moore <Eric.Moore@lsil.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>