[SCSI] hpsa: Do not zero fields of ioaccel2 command structure twice

Structure was already memset to zero at the top
of hpsa_scsi_ioaccel2_queue_command

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