[SCSI] hpsa: use scan_start and scan_finished entry points for scanning

use scan_start and scan_finished entry points for scanning and route
the CCISS_REGNEWD ioctl and sysfs triggering of same functionality
through hpsa_scan_start.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>