scsi: hpsa: Correct rare oob condition

There are some rare conditions where a spare is first in the device list
causing an array out-of-bounds condition.

Link: https://lore.kernel.org/r/159528197176.24772.14659026352708896249.stgit@brunhilda


Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Reviewed-by: Scott Benesh <scott.benesh@microsemi.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>