mptsas: fix checks for dma mapping errors

mptsas_smp_handler() checks for dma mapping errors by comparison
returned address with zero, while pci_dma_mapping_error() should be
used.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Sathya Prakash Veerichetty <sathya.prakash@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>