scsi: mpt3sas: Call sas_remove_host before removing the target devices

Call sas_remove_host() before removing the target devices in the driver's
.remove() callback function(i.e. during driver unload time).  So that
driver can provide a way to allow SYNC CACHE, START STOP unit commands
etc. (which are issued from SML) to the target drives during driver unload
time.

Once sas_remove_host() is called before removing the target drives then
driver can just clean up the resources allocated for target devices and no
need to call sas_port_delete_phy(), sas_port_delete() API's as these API's
internally called from sas_remove_host().

Signed-off-by: Suganath Prabu <suganath-prabu.subramani@broadcom.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>