[SCSI] mpt2sas : Rescan topology from Interrupt context instead of work thread

Following host reset its possible that the controller firmware could
assign new handles for devices, as well as adding or deleting devices. There is
code in the driver that will rescan the topology folowing host reset; updating
device handles, and remove devices that are no longer responding. This patch
will improve the responsivness by moving this rescaning from the delayed hotplug
worker thread to immediately following the host reset.

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Reviewed-by: Eric Moore <Eric.moore@lsi.com>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>