scsi: aacraid: report -ENOMEM to upper layer from aac_convert_sgraw2()

aac_convert_sgraw2() kmalloc memory and return -1 on error, which should
be -ENOMEM. However, nobody is checking return value, so with this
change, -ENOMEM is propagated to upper layer.

Signed-off-by: Nikola Pajkovsky <npajkovsky@suse.cz>
Reviewed-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>