[SCSI] ibmvscsi: Correct DMA mapping leak

The ibmvscsi client driver is not unmapping the SCSI command after
encountering a DMA mapping error while trying to map an indirect
scattergather list for the event pool.  This leads to a leak of DMA
entitlement that could result in the device failing future DMA operations
in a CMO environment.
Signed-off-by: NRobert Jennings <rcj@linux.vnet.ibm.com>
Acked-by: NBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/ibmvscsi/ibmvscsi.c

@@ -432,6 +432,7 @@ static int map_sg_data(struct scsi_cmnd *cmd,
 				sdev_printk(KERN_ERR, cmd->device,
 				            "Can't allocate memory "
 				            "for indirect table\n");
+			scsi_dma_unmap(cmd);
 			return 0;
 		}
 	}