scsi: qla2xxx: Fix DMA mapping test in qla24xx_get_port_database()

dma_map_XXX() functions return as error values DMA_MAPPING_ERROR which is
often ~0.  The error value should be tested with dma_mapping_error() like
it was done in qla26xx_dport_diagnostics().

Fixes: 818c7f8 ("scsi: qla2xxx: Add changes in preparation for vendor extended FDMI/RDP")
Signed-off-by: Thomas Fourier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>

Author: Thomas-fourier

drivers/scsi/qla2xxx/qla_mbx.c

@@ -2147,7 +2147,7 @@ qla24xx_get_port_database(scsi_qla_host_t *vha, u16 nport_handle,
 
 	pdb_dma = dma_map_single(&vha->hw->pdev->dev, pdb,
 	    sizeof(*pdb), DMA_FROM_DEVICE);
-	if (!pdb_dma) {
+	if (dma_mapping_error(&vha->hw->pdev->dev, pdb_dma)) {
 		ql_log(ql_log_warn, vha, 0x1116, "Failed to map dma buffer.\n");
 		return QLA_MEMORY_ALLOC_FAILED;
 	}