ieee1394: sbp2: enforce 32bit DMA mapping

In order to use OHCI-1394 physical DMA, all s/g elements, s/g tables,
ORBs, and response buffers have to reside within the first 4 GB of the
FireWire controller's physical address space.  Set the correct mask for
DMA mappings.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/ieee1394/sbp2.c

@@ -757,6 +757,11 @@ static struct sbp2_lu *sbp2_alloc_device(struct unit_directory *ud)
 			SBP2_ERR("failed to register lower 4GB address range");
 			goto failed_alloc;
 		}
+#else
+		if (dma_set_mask(hi->host->device.parent, DMA_32BIT_MASK)) {
+			SBP2_ERR("failed to set 4GB DMA mask");
+			goto failed_alloc;
+		}
 #endif
 	}