[SCSI] mpt2sas: Modify code to support Expander switch

Issue : Switch swap doesn't work when device missing delay is enabled.

(1) add support to individually add and remove phys to and from
existing ports. This replaces the routine
_transport_delete_duplicate_port.
(2) _scsih_sas_host_refresh - was modified to change the link rate
from zero to 1.5 GB rate when the firmware reports there is an
attached device with zero link.
(3) add new function mpt2sas_device_remove, this is wrapper function
deletes some redundant code through out driver by combining into one
subrountine
(4) two subroutines were modified so the sas_device, raid_device, and
port lists are traversed once when objects are deleted from the list.
Previously it was looping back each time an object was deleted from the
list.

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>