[SCSI] hpsa: update raid offload status on device rescan

When rescanning for logical drives, store information about whather
raid offload is enabled for each logical drive, and update the driver's
internal record of this.

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