Revert "[SCSI] mpt2sas: Remove phys on topology change."

Revert "[SCSI] mpt2sas: Remove phys on topology change."

This reverts commit 3520f9c779bed098ca76dd3fb6377264301d57ed
("mpt2sas: Remove phys on topology change")

Reverting the previous mpt2sas drives patch changes,
since we will observe below issue

Issue:
Drives connected Enclosure/Expander will unregister with
SCSI Transport Layer, if any one remove and add expander
cable with in DMD (Device Missing Delay) time period or
even any one power-off and power-on the Enclosure with in
the DMD period.

Cc: <stable@vger.kernel.org>
Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>