scsi: hpsa: correct ioaccel2 chaining

- set ioaccel2_sg_element member 'chain_indicator' to IOACCEL2_LAST_SG for
  the last s/g element.

- set ioaccel2_sg_element member 'chain_indicator' to IOACCEL2_CHAIN when
  chaining.

Reviewed-by: Bader Ali - Saleh <bader.alisaleh@microsemi.com>
Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Reviewed-by: Matt Perricone <matt.perricone@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>